tolong di jawab ya pakai cara!!

a.
3x-45 = x+23
3x-x = 45+23
2x = 68
x = 68/2
x = 34

b.
bcf = 180- sudut GCF
bcf = 180-(x+23)
bcf = 180- (34+23)
bcf = 180 - 57
bcf = 123