Answer
5 and -4
Explanation
If the two triangle are congruent then they have the same area.
20 = x² - x
x² - x - 20 = 0
x² - x + (1/2)² = 20 + (1/2)²
(x - 1/2)² = 20.25
x - 1/2 = √20.25
x - 1/2 = 4.5 or x - 1/2 = - 4.5
x = 4 1/2 + 1/2 x = -4 1/2 + 1/2
= 5 = -4
The values of x are 5 and -4.
