How do you solve this system of equations using substitution?

Question

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

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Answer 1 · 2017-03-15T19:23:39

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

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

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

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

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

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

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

$- 5 x + 9 = 14$ $-5x +9 = 14$

$- 5 x = 14 - 9$ $-5x = 14-9$

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

$x = \frac{5}{- 5} = - 1$ $x = 5/-5 = -1$