Question 1117540
given:
{{{x-4y=-7}}}

({{{x}}},{{{y}}})=({{{x}}} ,{{{5}}}) =>{{{y=5}}}

{{{x-4y=-7}}}...substitute {{{y=5}}}
{{{x-4*5=-7}}}
{{{x-20=-7}}}
{{{x=20-7}}}
{{{x=13}}} ->({{{13}}} ,{{{5}}})

({{{x}}},{{{y}}})=({{{-15}}}, {{{y}}}) =>{{{x=-15}}}

{{{x-4y=-7}}}...substitute {{{x=-15}}}
{{{-15-4y=-7}}}
{{{-15+7=4y}}}
{{{4y=-8}}}
{{{y=-2}}} ->({{{-15}}} ,{{{-2}}})


{{{drawing( 600, 600, -20, 20, -20, 20,
circle(-15,-2,.12),circle(13,5,.12),
locate(-15,-2,p(-15,-2)),locate(13,5,p(13,5)),
 graph( 600, 600, -20, 20, -20, 20, x/4+7/4)) }}}