Question

one angle is 2/3 of its supplementary angle is 180 degree. find its magnitude?

Answer 1

let one supplementary angle be x.
thus,
2/3x + x = 180
(2x + 3x)/3 = 180
2x + 3x = 180 * 3
5x = 180 * 3
x = (180 * 3)/5
   = 36*3
   = 108 degrees.
therefore the angle is 2/3 of x = (2/3)*108 = 72  degrees.