Question

The Robertson's find that have used 1/2 gallon of paint to cover 480 square feet of wall. They used 3/4 gallon of paint to cover 720 square feet of wall. Write an equation to find the number of gallons of paint they will need (G), in order to cover S square feet of wall.

Thanks in advance for any help. I really need to see HOW to equation is worked out, so if you can help set up the equation, I don't mind if you don't give me the answer.

Answer 1

look at it as 2 ordered pairs
(1/2 , 480) and (3/4 , 720)
and find the linear equation

slope = (720-480)/(3/4 - 1/2)
= 240/(1/4) = 960

S = 960g + b , (using y = mx + b )
for (1/2, 480)
480 = 960(1/2) + b
480 = 480 + b
b = 0

S = 960G

(tells me 1 gallon covers 960 square feet)

Answer 2

Thank you so much!! When you set it up as a slope intercept equation, it is much easier to solve. I get it now :)