Answer:
10m - 7n - 14
Step-by-step explanation:
Given Q = 7m + 3n, R = 11 - 2m, S = n + 5, and T = -m - 3n + 8
[Q - R] + [S - T].
= (7m + 3n - 11 + 2m) + (n + 5 + m + 3n - 8)
collect all the like terms
= 7m +2m +m +3n + n + 3n - 11 - 8 + 5
= 10m + 7n - 14
The third option 10m - 7n - 14 is right
