Final answer:
To find the value of x for which the angles (2x-20)° and 90° are perpendicular, set the two angles equal to each other and solve for x. The value of x is 10, so the correct answer is a) x = 55.
Step-by-step explanation:
To find the value of x for which the angles (2x-20)° and 90° are perpendicular, we need to set the two angles equal to each other. Since perpendicular angles have a sum of 90°, we can write the equation (2x-20)° + 90° = 90°. Now, solve for x:
(2x-20)° + 90° = 90°
2x - 20 = 0
2x = 20
x = 10
Therefore, the value of x for which the angles (2x-20)° and 90° are perpendicular is x = 10. This means that the correct answer is a) x = 55.