Question 118195
If the answer is (-3,4), then substitute for x and y in your equations.
First find b.
{{{5x+7y=b}}}
{{{5(-3) + 7(4) = b}}}
{{{-15+28=b}}}
{{{b=13}}}
Next find m. 
{{{mx+y=22}}}
{{{m(-3)+4=22}}}
{{{-3m+4=22}}}
{{{-3m=18}}}
{{{m=-6}}}