Question

Find the magnitude of an angle which is 2/3 of its supplement

Answer 1

Let one angle is x then its supplementary angle is 2x/3
x + 2x/3 = 180
5x/3 = 180
x = 108
supplementary angle is 2*108/3 = 72

Answer 2

let the angle be 2x
so it's supplement will be 3x
=> 2x +3x = 180°
=> 5x = 180°
=> x = 36 °

=> required angle will be 2x = 2× 36° = 72°