Hi!
We will firstly solve the two equations by the elimination method.
m-n=1
m+n=3
Now we add the equations together. Because n and -n are opposites, the first step is practically already completed for us.
m-n=1
2m=4
And it is pretty straight forward here.
m-n=1
m=2
Now we put m into the first equation and find n.
2-n=1
m=2
n=1
m=2
The answer is b) 2.
