How do you solve this system of equations using substitution?

Question

$y=-3$
$-5x-3y=14$

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Answer 1 · 2017-03-15T19:23:39

$x = -1" "and" " y --3$

$y = -3" and " -5x-3y = 14$

This is a really simple system of equations to solve, because we have already been given the value of one of the variables:

$color(red)(y =-3)$

So now you can substitute $-3$ for $y$ in the other equation:

$-5x -3color(red)(y) = 14$

$-5x -3(color(red)(-3)) = 14$

$-5x +9 = 14$

$-5x = 14-9$

$-5x =5" "larr div -5$

$x = 5/-5 = -1$