given: d=6, l=25, w=15
need to find areas of all surfaces but the top because its a pool and the top is exposed:
2ld + 2dw + lw
2(25)(6) + 2(6)(15) + (25)(15) =
300 + 180 + 375 = 855 ft²
you need to paint 855ft² of interior surface of the pool. the question asked how much paint is needed though, so there is not enough info provided to answer that. once you know how much paint covers 1ft² then you can multiply by 855.