Answer:
see explanation
Step-by-step explanation:
The area (A) of a trapezium is calculated as
A = h (a + b)
where a, b are the measures of the parallel sides and h the perpendicular distance between them.
here h = x - 5, a = x + 6 and b = x + 2, thus
A = (x - 5)(x + 6 + x + 2) = 36
Multiply both sides by 2 to clear the fraction
(x - 5)(2x + 8) = 72 ← expand left side
2x² - 2x - 40 = 72 ← divide through by 2
x² - x - 20 = 36 ( subtract 36 from both sides )
x² - x - 56 = 0 ← as required