Answer :
The area to be covered by the paint = 875 sq ft.
Number of gallons used = 7 gallons.
Area covered by 1 gallon is calculated as,
[tex]\begin{gathered} Area\text{ covered by 1 gallon = }\frac{875}{7} \\ Area\text{ covered by 1 gallon = 125 sq ft} \end{gathered}[/tex]Area covered by 35 gallons is calculated as,
[tex]\begin{gathered} Area\text{ covered by 35 gallons = 35 }\times\text{ 125 sq ft.} \\ Area\text{ covered by 35 gallons = 4375 sq ft.} \end{gathered}[/tex]Thus area covered by 35 gallons is 4375 sq ft.