#### Answer

Area = 22.5 square ft

#### Work Step by Step

The area of the trapezoid is equal to $\frac{1}{2}$ $\times$ (b + B) $\times$ h
Area = $\frac{1}{2}$ $\times$ (5 ft + 10 ft) $\times$ 3 ft
Area = $\frac{1}{2}$ $\times$ (15 ft) $\times$ 3 ft
Area = 22.5 square ft