bantuin ya! klo perlu dgn caranya pliss

2x + 40 = 130 ===> sudut bertolak belakang

===> 2x = 90 ===> x = 45

y + 10 = 40 ===> sudut bertolak belakang

===> y = 30

3z + 20 = 80 ===> sudut bertolak belakang

===> 3z = 60 ===> z = 20
 
Jadi x + y - z = 45 +30 - 20 = 55 .... ( C )