Question

jenn has $150 saved for lunch money. each day she takes out $2.50 for lunch write the equation for this function???D:

Answer 1

What we know so far is that the equation is linear, correct?

Answer 2

im sorry replace the word equation with formula
the section im in is called arithmetic and geometric sequencing if that helps

Answer 3

we could still y=mx+b if I'm not mistaken

Answer 4

sounds about right

Answer 5

Okay, so far we know that we have two numbers. The total of 150 and 2.50, now we need to figure out which one gets the variable x

Answer 6

wouldnt 2.50 get the x?

Answer 7

Yes it would, and instead of it being y=mx+b it's gonna be y=b-mx because we are taking out money not adding some.

Answer 8

Let m = money Jenn has

She starts with m = 150 before spending any money on lunches

On day 1, she takes out $2.50, so she ends up with m = 150 - 2.50

On day 2, she starts with m = 150 - 2.50 = 147.50, and she spends another 2.50, so she ends up with m = 147.50 - 2.50, but this is also m = 150 - 2.50 - 2.50 or
m = 150 - 2*2.50, She took out 2 times 2.50, one times 2.50 on day one and one times 2.50 on day 2.

On day 3, she ends up with 150 - 2.50 - 2.50 - 2.50 or
m = 150 - 3*2.50

Let d = number of the day

On any day d, she will end up with m = 150 - d*2.50 after paying for lunch.

The formula then is
m = 150 - 2.5d
Where m = the money she will have after paying for lunch on day d.

Now that you have the formula, a question you can ask is how many days will it take for her to spend all her money. That means after spending 2.50 in the last day, she will have 0 dollars left. That is when m = 0.
Solve 0 = 150 - 2.5d for d, to find out.

Answer 9

... Yea pretty much what mathstudent explained :l