Question 107070
Since the solution is (-3,4) we will use x=-3 and y=4


Substituting x=-3 and y=4 to {{{mx+3y=8}}}

{{{-3m+3(4)=8}}}
{{{-3m+12=8}}}
{{{-3m+12-12=8-12}}}
{{{-3m+0=-4}}}
{{{-3m=-4}}}
{{{(-3m)/(-3)=(-4)/(-3)}}}
{{{m=4/3}}}


Substituting x=-3 and y=4 to {{{-3x+4y=b}}},

{{{-3(3)+4(4)=b}}}
{{{-9+16=b}}}
{{{b=7}}}



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