Question 459938
m=3 n=9
2m=n-3
3m=2n-9
substitution
n=2m+3
3m=2(2m+3)-9
3m=4m+6-9
3m=4m-3
0=m-3
3=m
2*3=n-3
6=n-3
9=n


check
6=9-3
6=6

9=18-9
9=9
ok