Question

Simplify -3xy 3 + 7xy 3 + (-xy 3) + (-3xy 3).

Answer 1

I thing the answer is 75 I may be wrong but that’s what I got

Answer 2

-3xy 3 + 7xy 3 + (-xy 3) + (-3xy 3).

First combine like terms:
-3xy 3 + (-3xy 3) + 7xy 3 + (-xy 3)

-3xy3 +  -3xy3 = -6xy3
7xy3 + -xy3 = 6xy3

The answer is 7xy3 + 6xy3