Using the fact that this is a right triangle and that the sum of the interior angles must be 180°, we will see that x = 55.
How to find the value of x?
We know that this is a right triangle, and we also know that the sum of the interior angles of any triangle is 180°, then we can write the following equation.
∠6 + ∠8 + 90° = 180°
Replacing the angles that we know we get
x + (x - 20) = 180 - 90
2x - 20 = 90
2x = 90 + 20
2x = 110
x = 110/2 = 55
That is the value of x.