tolong.. di jawab ya.. yang menjawab. terimakasih sekali..

38.
3a = 120
a = 120/3
a = 40

120 + 5c = 180
5c = 180 - 120
5c = 60
c = 60/5
c = 12

a + c = 40+12 = 52

39.
8x - 72 = 3x + 48
8x - 3x = 72 + 48
5x = 120
x = 24

40.
a + b + b = 180
a + 2b = 180

2a + a + b = 180
3a + b = 180 → 6a + 2b = 360

6a + 2b = 360
a + 2b = 180
--------------------- (-)
5a = 180
a = 180/5
a = 36

a + 2b = 180
36 + 2b = 180
2b = 180 - 36
2b = 144
b = 72