Tolong dongg please thxxx

7x = 180-40
7x = 140
x = 20

7x = 80 + 2y
140 = 80 + 2y
2y = 140-80
2y = 60
y = 30

4z = 180 - 2y - 40
4z = 180 - 60 - 40
4z = 80
z = 20

a. nilai x = 20 ; nilai y = 30 ; nilai z = 20
b. x = 140° ; y = 60° ; z = 80°

x = 40 + 7x = 180
7x = 180 - 40
7x = 140
x. = 140 : 7
x = 20
y = 80 + 2y + 40 = 180
120 + 2y = 180
2y = 180 - 120
2y = 60
y = 30
z = 4z + 2y + 40 = 180
4z + 2.30 + 40 = 180
4z + 60 + 40 = 180
4z + 100 = 180
4z = 180 - 100
4z = 80
z = 20

= x + y + z
20 + 30 + 20
= 70 derajat