Two angles form a linear pair, linear pairs add up to 180°. so x° + y° = 180°
One angle is twice the measure of the other, so y°•2 = x°
Plug in the new value
(y°•2) + y°= 180°
2y° + y°= 180°
3y° = 180°
y° = 60°
Therefore, x°= 120°
120°+60°=180°
Have a good day