please help me i don't get this stuff i am only in 6th grade

Answer:
Option D.
Step-by-step explanation:
You can do this two ways.
1. You can simplify both expressions.
2(m+m+m)+m = 2*3m+m = 7m
(3+4)m = 7m
Also, you can test each answer. Substitute all the m's for 4s and solve.