Question 120643
If we require that the solution is (-3,4),

{{{5(-3)+7(4)=13=b}}} Substitute values for x and y into the first equation

and 

{{{m(-3)+4=22}}} Substitute values for x and y into the second equations
{{{-3m=18}}} Subtract 4 from both sides
{{{m=-6}}} Divide both sides by -3


then, m=-6, b=13 makes this system true.