Question

WRITING LINEAR EQUATIONS FROM WORD PROBLEMS Addison painted her room. She had 50 square meters to paint, and she painted at a constant rate. After 2 hours of painting, she had 35 square meters left. Write an equation for the relationship between the area and number of hours.

Answer 1

Let:

y = total square meters to paint

x = number of hours

$\begin{gathered} \text{Write the equation in the slope intercept form:} \\ y(x)=mx+b \\ \text{ In this case:} \\ y(x)=50-mx \\ \text{After 2 hours she had 35 square meters left, so:} \\ x=2 \\ y(2)=35=50-2(m) \\ 35=50-2m \\ \text{Solve for m:} \\ 15=2m \\ m=\frac{15}{2}=7.5 \\ So\colon \\ y(x)=50-\frac{15}{2}x \end{gathered}$