By definition, the formula for finding the area of a trapezoid is
 A = [(b1 + b2) x h] / 2
 Where,
 b1: Base 1
 b2: Base 2
 h: height, or distance between bases.
 Substituting we have:
 A = ((5 + 4) * (2.5)) / 2
 A = 11.25 feet ^ 2
 Answer:Â
 the area of the seat is:
 A = 11.25 feet ^ 2