Question 363774
Let x = length of upper base
 
Area = h * (upper base + lower base)/2

15d * (x + x + 10)/2 = 185d

Multiply both sides by 2/15

       2x + 10d   = 185d (2/15)
             2x  = 24.67d - 10d
              2x  = 14.67d
               x  = 7.33d