Let the pair of supplementary angles be x and y [and x > y]
then we have x + y = 180° …… (1)
By problem, x = y + 18°
⇒ x – y = 18° …… (2)
Solving the equations (1) and (2) we get
and x = 198/2 = 99°
Substituting x = 99° in equation (2)
we get 99° – y° = 18°
⇒ y° = 99° – 18 = 81°
∴ The angles are 99° and 81°.
