Question 862048
m - n = 7         (1)
3m + 2n = 6       (2)

solve for m from (1)

m=7+n  (3)

now substitute (3) into (2) for m 

3(7+n)+2n=6

21+3n+2n=6
21+5n=6

5n=6-21
n=-15/4
n=-3


no plug n=-3 into (1)
m - (-3) = 7  
m=4