What are the values of X, Please give me an in-depth explanation so that I can answer similar problems on my own

Step-by-step explanation:
a line is 180°
180-90 (given) = 90
so the two angles x and 2x added together equal 90
2x + x = 90
3x = 90
x = 30
the angles are 30 and 2(30)= 60