we need to find two areas and sum to find the total area
the first area is the stairs
we must find the area of the trapezoid by the formula
where B is the long side, b the short side and h the height
so, the area of the stairs is 10 feet squared
The second area is the pool
the area of the rectangle is
replacing
the area of the pool is 392 feet squared
Then, the toal area is the sum,so
the total Area is 402 feet squared, so the rigth option is D