Two angles whose sum is 90° are called complementary angles.
It is given that the angles (2x – 5)° and (x – 10)° are the complementary angles.
∴ (2x – 5)° + (x – 10)° = 90°
⇒ 3x° – 15° = 90°
⇒ 3x° = 90° + 15° = 105°
⇒ x° = = 35°
Thus, the value of x is 35.