# How do you solve this system of equations using substitution?

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

Mar 15, 2017

$x = - 1 \text{ "and" } y - - 3$

#### Explanation:

$y = - 3 \text{ and } - 5 x - 3 y = 14$

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

$\textcolor{red}{y = - 3}$

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

$- 5 x - 3 \textcolor{red}{y} = 14$

$- 5 x - 3 \left(\textcolor{red}{- 3}\right) = 14$

$- 5 x + 9 = 14$

$- 5 x = 14 - 9$

$- 5 x = 5 \text{ } \leftarrow \div - 5$

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