<PRE><B>Question 457153</B>
3m + n = 17
m - 7n = 57
:
We will use the 2nd equation for substitution
m = 7n + 57
:
Replace m with (7n+57) in the 1st equation
3(7n+57) + n = 17
21n + 171 + n = 17
21n + n = 17 - 171
22n = -154
n = {{{(-154)/22}}}
n = -7
find m
m = 7(-7) + 57
m = -49 + 57
m = +8
:
Check solutions in the 2nd equation
m - 7n = 57
8 - 7(-7) = 57
8 + 49 = 75</PRE>