Question 862163
1.{{{ax+by=0}}}
2.{{{x+y-c=0}}}
Multiply eq. 2 by {{{-a}}} and add to eq. 1,
{{{ax+by-ax-ay+ac=0}}}
{{{by-ay=-ac}}}
{{{y(b-a)=-ac}}}
{{{highlight(y=-(ac)/(b-a))}}}
.
.
{{{x-(ac)/(b-a)-c=0}}}
{{{x=c+(ac)/(b-a)}}}
{{{x=(c(b-a))/(b-a)+(ac)/(b-a)}}}
{{{x=(cb-ca+ac)/(b-a)}}}
{{{highlight(x=(bc)/(b-a))}}}