# How do you solve the system y = 5x - 7 and -4 + y = -1  by substitution?

May 21, 2015

$y = 5 x - 7$ ..........equation $\left(1\right)$

$- 4 + y = - 1$ ......equation $\left(2\right)$

substituting equation $\left(1\right)$ in equation $\left(2\right)$

$- 4 + y = - 1$
$- 4 + \left(5 x - 7\right) = - 1$
$5 x - 11 = - 1$
$5 x = 10$
$x = 2$

substituting the value of $x$ in equation $\left(1\right)$
$y = 5 x - 7 = 5. \left(2\right) - 7$
$y = 10 - 7 = 3$

The solutions for the system of equations are :
$\textcolor{b l u e}{x} = 2$
$\textcolor{b l u e}{y} = 3$