Solve system of equation . Check by substitution?

Question

4m+n=17
3m-4n=27

Answer 1

Multiply first equation by 4

16m + 4n = 68
3m - 4n = 27

Add

19m = 95
m =5

Substitute in either equation to get n

3(5) - 4n = 27
-4n = 12
n = -3.

Answer 2

Multiplying 4m+n=17 by 4 and adding it to 3m-4n=27
16m+4n=68
3m-4n=27
__________
19m=95
or,m=95/19=5
Putting the value of m in the first equation,
4X5+n=17
or,n=17-20=-3