If the supplement of an angle is two-third of itself ,then its supplement is

( 'x' is not 144 .) The supplement of an angle is (180 - x) .The problem says that (2/3) of 'x' is equal to (180 - x) .180 - x = 2/3 xMultiply each side by 3 : ( Note:  3 x 180 = 540 .) 540 - 3x = 2xAdd 3x to each side:540 = 5xDivide each side by 5 :x = 108° .