Let the larger angle = x Let the smaller angle = y According to question, x = y + 18 … (1) Both angles are supplementary, therefore x + y = 180 … (2) Putting the value of x in equation (2), we get y + 18 + y = 180 ⇒ 2y = 162 ⇒ y = 81 Putting the value of y in equation (1), we get x = 81 + 18 = 99 Hence, one angle is 81° and the other one is 99°.