Menghitung sudut ini, caranya bagaimana yaa?

→ Sudut = x ←

3a + 20 + 90 = 11a - 10
3a + 110 = 11a - 10
8a = 120
a = 120 / 8
a = 15

x + 3a + 20 = 90
x + 3(15) = 90 - 20
x + 45 = 70
x = 70 - 45
x = 25