Answer:
a) 9a + 6b
b) 5c - 3d
Step-by-step explanation:
a)
4a + 7b + 5a - b =
= 4a + 5a + 7b - 1b
= 9a + 6b
b)
6c + 4d - c - 7d =
= 6c - 1c + 4d - 7d
= 5c - 3d
