Question 536435
{{{3x-9y=69}}}.............(1)
{{{5x+25=y}}}..............(2)
Put the value of y in (1)
{{{3x-9(5x+25)=69}}}
{{{3x-45x-225=69}}}
{{{-42x=69+225}}}
{{{-42x=294}}}
Divide by -42 both sides
{{{-42/-42x=294/-42}}}
{{{cross(-42)/cross(-42)x=-cross(294)/cross(42)}}}
{{{x=-7}}}
Put the value of x in (1)
{{{3x-9y=69}}}
{{{3(-7)-9y=69}}}
{{{-21-9y=69}}}
{{{-9y=69+21}}}
{{{-9y=90}}}
Divide by -9 both sides
{{{-9y/-9=90/-9}}}
{{{cross(-9)y/cross(-9)=-cross(90)/cross(9)}}}
{{{y=-10}}}

x,y=-7,-10



Check
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Put the values of x and y in (1)
{{{3x-9y=69}}}.............(1)
{{{3(-7)-9(-10)=69}}}
{{{-21+90=69}}}
{{{69=69}}}
Put the values of x and y in (2)
{{{5x+25=y}}}..............(2)
{{{5(-3)+25=-10}}}
{{{-15+25=-10}}}
{{{-10=-10}}}