Question 997949
Solve the systems of equations by substitution: 

{{{3x+y= -8}}}....eq.1
{{{4x+3y=7}}}....eq.2
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start with {{{3x+y= -8}}}....eq.1, solve for {{{y}}}

{{{y=-3x -8}}}...eq.1a...now, substitute it in eq.2

{{{4x+3(-3x -8)=7}}}....eq.2....solve for {{{x}}}

{{{4x-9x -24=7}}}

{{{-5x -24=7}}}

{{{-7 -24=5x}}}

{{{ -31=5x}}}

{{{x= -31/5}}}

{{{highlight(x= -6.2)}}}....now, go back to {{{y=-3x -8}}}...eq.1a,substitute {{{-6.2}}} for {{{x}}} and find {{{y}}}

{{{y=-3(-6.2) -8}}}

{{{y=18.6 -8}}}

{{{highlight(y=10.6) }}}


{{{drawing( 600, 600, -15, 15, -15, 20,
circle(-6.2,10.6,.2), locate(-6.2,10.6,p(-6.2,10.6)),
 graph( 600, 600, -15, 15, -15, 20, -3x -8,-(4/3)x+7/3)) }}}