Respuesta :

316628

Answer:

A. 7

Step-by-step explanation:

3m + 21 = 6m

Move variables to one side to get:

3m + 21 = 6m

-3m         -3m

21 = 3m

Then isolate variable by dividing by 3

21/3 = 3m/3

m = 7

Choice A is the correct answer