Answer : The length of each base of the trapezoidal yard are, 36 and 24 feet.
Explanation :
Let the longer base of trapezoid be, x
So, the shorter base of trapezoid is, (x-12)
As we are given that:
Area of trapezoid = 1650 square feet
Formula for the area of trapezoid is:

where,
A = area of trapezoid
= longer base length
= shorter base length
h = height
Now put all the given values in the above formula, we get:

By the solving the terms, we get the value of 'x'.
x = 36
Thus, the value of x = 36 feet
The longer base of trapezoid = x = 36 feet
The shorter base of trapezoid = (x-12) = 36 - 12 = 24 feet
Thus, the length of each base of the trapezoidal yard are, 36 and 24 feet.