To add 2m/7 and 3m/14 you must make sure that their denominators are the same. To do this you must rewrite 2m/7 as 4m/14. They are both equal.
4m/14 + 3m/14 = 1
Add like terms.
7m/14 = 1
Multiply by 14 on both sides.
7m = 14
Divide by 7 on both sides.
m = 2
m = 2