Answer:
-m^3 - 3m^2 +2m -4
Step-by-step explanation:
(m^3-3m^2+m-1)-(2m^3-m+3)
Distribute the minus sign
(m^3-3m^2+m-1)-2m^3+m-3
I like to line them up vertically
m^3-3m^2+m-1
-2m^3 +m-3
--------------------------