Question 701106
{{{x+y=9}}} ......eq. 1

{{{x=2y}}}...eq. 2......substitute in eq. 1


{{{2y+y=9}}}...solve for {{{y}}}

{{{3y=9}}}

{{{y=9/3}}}

{{{highlight(y=3)}}}

now find {{{x}}}

{{{x=2y}}}....substitute {{{y}}}

{{{x=2*3}}}

{{{highlight(x=6)}}}