Pls help I am stuck, or having a brain fart I cant tell yet.

Answer:
-4r³s -3r² +2rs -5
Step-by-step explanation:
The powers of r in each of the terms from left to right are ...
3, 1, 0, 2
Arranging these in descending order gives the sequence of terms ...
-4r³s -3r² +2rs -5