Welcome to a lesson on problem solving, using addition and subtraction and whole
numbers.
More specifically, our goals are to interpret a pie chart
and then answer questions using addition and subtraction.
Here we see a pie chart that represents an individuals
monthly expenses, broken into categories. The categories are rent,
food, transportation, school, and entertainment. And a pie chart is a nice way to
represent,
because it gives a visual of how much of the total each category represents,
in this case for monthly expenses. So this blue collar here represents the rent,
and this individual spends six hundred dollars a month on rent.
Let's go ahead label that. The red region represents the
amount of money spent on food per month, which is two hundred fifty dollars.
So notice how the piece of the pie that represents six hundred dollars
is more than twice the size of the piece of pie that represents the
monthly expense of food. Transportation expenses is in green
and it represents three hundred twenty-five dollars. This purple region
here represents school expenses,
which is five hundred seventy-five dollars a month. And this piece here represents
entertainment expenses per month of one hundred fifty dollars.
So the first question asked.
If these were your monthly expenses, how much will you need
on a monthly basis to cover your expenses? So we'll have to sum
all of these expenses, to determine the total monthly expenses.
So we'll have six hundred, two hundred fifty, three hundred twenty-five,
five hundred seventy-five and one hundred fifty.
So we'll start by adding the ones column. So zero, plus zero, plus five, plus five, plus zero,
that'll be ten.
So we have a zero in the ones column, and we carry
one to the tens column. So one plus five,
that's six, plus two that's eight, plus seven that's fifteen,
plus five that would be twenty. So we put a zero in the tens column
and carry two over to the hundreds column. So we have two plus six that's
eight, plus two is ten, plus three is thirteen,
plus five is eighteen, plus one is nineteen. So we have nineteen hundred dollars or one
thousand
nine hundred dollars of monthly expenses based upon the given information.
So the next question asked. If you are currently bringing home
two thousand twelve dollars per month, can you cover your expenses?
Well, two thousand twelve is greater than
one thousand nine hundred. So yes, you can cover your expenses.
The next question is, can you save any money per month,
bringing home this much money per month, with one thousand, nine hundred dollars
of expenses? To determine how much you can save,
we would take the amount earned per month, two thousand twelve,
and subtract the monthly expenses.
And this would give us how much we could save on a monthly basis.
So two minus zero would be two,
one minus zero is one. Here we could take twenty minus nineteen,
or you may want to think of borrowing one from the two,
and then we'd have a ten in the hundreds column. So ten minus nine would give us one.
In the thousands place value we have one minus one which is zero.
So we can save a total of one hundred twelve dollars per month,
based upon the given information. Now let's take a look at one more question.
If your education expenses increased to seven hundred dollars per month,
and you get a roommate to pay half of the rent, do you have enough money per
month?
Let's first take a look at how much the education expenses have increased.
It's increasing to an amount of seven hundred dollars per month
when currently it is five hundred seventy-five dollars per month.
So if the new amount is seven hundred dollars,
and the old amount was five hundred seventy-five dollars,
we can subtract to determine how much it has increased.
So let's start by doing this. So we'll have to borrow from the seven, this will be a six,
this would be a ten but we're going to have to borrow from here to get enough in the ones column. So
this would be a nine and this would be a ten.
So ten minus five, that would be five.
Nine minus seven that would be two. And then six minus five would be one. So it's an
increase of one hundred twenty-five dollars.
Remember our total expenses before the increase was nineteen hundred dollars.
So the new total for our monthly expenses would be nineteen hundred dollars,
plus the increase of one hundred twenty-five dollars.
Go ahead and add. So our new total per month is two thousand twenty-five dollars.
We were also told we'd bring home two thousand twelve hundred dollars per month,
which would not be enough to cover our new monthly expenses.
So if you get a roommate that pays half of the rent,
and the current rent is six hundred dollars. Well half of six hundred dollars as three
hundred dollars.
So your rental expense would decrease by three hundred,
therefore decrease the total monthly expenses by three hundred dollars.
So if we take two thousand twenty five, and subtract three hundred dollars from this,
this will give us the new monthly expense with the roommate.
So five minus zero that's five. Two minus zero is two,
go ahead and borrow from the two. So we have ten minus three, that would be seven.
And then one minus zero would be one. So the new total for monthly expenses would be
one thousand seven hundred twenty-five dollars.
Which is obviously less than your monthly take home pay.
Therefore, with the changes listed in this problem,
you would still come in under budget. In fact even though your education expenses
have increased,
since you now have a roommate, we can see here that we can actually save more
money per month.
Let's go ahead determine what that monthly savings would be. If we take the
monthly income,
and subtract out the new monthly expenses,
we can determine how much we could save per month given this new situation.
So again, here we have to borrow from the one. So this would be twelve minus five, that'll be seven.
And could borrow again in the tens column, but there's zero in the hundreds column so we'll
go all the way over to the thousands column. We'll borrow one here,
this will become ten. But we're going to change it to nine because we're going to borrow.
And so now we have a ten in the tens column. Ten minus two would be
eight. Nine minus seven would be two.
And then one minus one is zero. So now, with this new situation, we can actually save
two hundred eight-seven dollars per month, which is actually even better,
as long as you can handle a roommate. I hope you found this example helpful.
Thank you for watching.