Step-by-step explanation:
The volume of paint used, V liters, is directly proportional to the area, A square feet, that the paint can cover.
This is written as:
\begin{gathered}V \propto A\\V=kA,$ where k is the constant of proportionality\end{gathered}
(a)5 liters of paint can cover a wall with an area of 75 square feet.
V=5 liters, A=75 square feet.
Substitution into V=kA
5=75k
k=5/75
\text{Constant of proportionality, k}=\dfrac{1}{15}Constant of proportionality, k=151
(b)Substitution of k=\dfrac{1}{15}k=151 into V=kA
The equation relating V and A is:
V=\frac{1}{15}AV=151A
(c)If A=180 Square feet
Volume of paint needed,
\begin{gathered}V=\frac{1}{15} X 180\\=12$ liters\end{gathered}
