Answer:
12p - 13q + 20rs
Explanation:
Subtract 8p + 9q -5rs from – 4p - 4 q +15 sr
– 4p - 4q + 15sr - (8p + 9q -5rs)
= -4p - 4q + 15sr - 8p - 9q + 5rs
= -4p - 8p - 4q - 9q + 15rs + 5rs
= -12p - 13q + 20rs
– 4p - 4q + 15sr - (8p + 9q -5rs) = 12p - 13q + 20rs