Answer:
5r - 5s
Step-by-step explanation:
Distribute
9(r - s) = 9r - 9s
-4(r - s) = -4r + 4s
9r - 9s - 4r + 4s
9r - 4r - 9s + 4s
9r-9s-4r-4s
9r-4r-9s-4s
5r-13s
