Answer:
9a + 6b and 5c - 3d
Step-by-step explanation:
(a)
4a + 7b + 5a - b ← collect like terms
= (4a + 5a) + (7b - b)
= 9a + 6b
(b)
6c + 4d - c - 7d ← collect like terms
= (6c - c) + (4d - 7d)
= 5c - 3d
All you've got to do is write an equation. EX 2n-1
(antique book age)*4 idrk the question but i hope this helps