# writing and solving equations

Discussion in 'Calculator Requests' started by TinaJena, Dec 9, 2016.

1. ### TinaJenaNew Member

My daughter is having issues with a math problem for her homework. she tells me that I am doing it wrong but I am getting the correct answer... Can you please look at it and see if i am correct?
The problem is:
A painter charges \$15.35 per hour, plus an additional amount for supplies. If he made \$141.73 on a job where he worked 4 hours, how much did the supplies cost?

I have the equation as: \$15.35 * 4 = \$141.73 - x ... I got the answer of \$80.33 for supplies

She is telling me that the teacher is wanting her to do the PEMDAS backwards but that is not working out for her and I am not understanding that at all. Any suggestions would help out

Thanks,
Tina

Here is how I set up the profit equation where h is the hours worked and x is the supply cost:
P(h) = 15.35h + x

We know P(4) = 141.73
P(4) = 15.35(4) + x
141.73 = 15.35(4) + x

Simplify
141.73 = 61.4 + x

Subtract 61.4 from each side:
x = 80.33