In the question, we are told that a gallon of paint covers 240ft^2.
Explanation
Since the gallon of paint covers an area of 240ft^2. It can be assumed that the brush is dipped into the gallon once and used to paint the area.
This implies that
Answer
One gallon would be used to paint the area with just one coat of paint.
Two gallons would be used to paint the area if the painter uses two coats of paint.
