#### Answer

15 cm

#### Work Step by Step

The area of a trapezoid whose bases have lengths b1 and b2 and altitude has length of h is given by
A = $\frac{1}{2}$*h(b1+b2)
Given Area A= 96 $cm^{2}$
h = 8 cm
b1 = 9cm
Therefore 96 = $\frac{1}{2}$*8* (9 + b2)
96 = 36 + 4 b2
4b2 = 96 - 36
4b2 = 60
b2 = $\frac{60}{4}$ = 15 cm
Length of the other base side = 15 cm