Tentukan nilai x pada gambar Pliss pakek jalan

a) bila sudut siku-siku
4x + 2x = 90
6x = 90
x = 90 : 6
x = 15
b) 2x + 3x + 90 = 180
5x + 90 = 180
5x = 180 - 90
5x = 90
x = 90 : 5
x = 18
c) 120 + x = 180
x = 180 - 120
x = 60