Question

If two angles are supplementary and one is 30 degree less than twice the other find the angles

Answer 1

x+y=180, 2x-y=30 So from elimination method we get x=70 and y=110

Answer 2

let one of the angle be x and the other be y.
y=2x-30
x+y=180
x+2x-30=180
3x-30=180
3x=180+30
3x=210
x=210/3
x=70

the two angles are 70 and 110