Answer:
7) a = 60; b = 100
8) c = 20
9) d = 45
Step-by-step explanation:
7)
a + 120 = 180
a = 60
b + 80 = 180
b = 100
8)
5c + 4c = 180
9c = 180
c = 20
9)
3d + d = 180
4d = 180
d = 45
