Question

the sum of an angle and two third of its supplement angle is 180 degrees, then find the angle.

Answer 1

let the angle be x
two third of it's supplement
= 2/3 × (180-x)
= 2/3×180 - 2/3 × x
= 2×60 - 2x/3
=120- 2x/3
= 360-2x/3

now the sum of angle and it's supplement is 180
x+ 360-2x/3=180
3x+360-2x/3= 180
x+360/3=180
x+ 360= 180×3
x+360=540
x= 540-360
x= 180

the angle is 180°