Question

the measure of an angle is twice the measure of its supplementary angles find the measure of angle

Answer 1

let the angle be x and y
x+y=180
x= 2y
substitute the value of y
2y+y=180
3y=180
y=60
2y=120 answer

Answer 2

let the angles be a°, b°
such that a°+b°=180°
a°=(180-b)°---------(1)
ATQ
a°=(2b)°-----------(2)
from(1)&(2)
(180-b)°=(2b)°
=>(3b)°=180°
=>b°=60°
from(2)
a°=120°