# How do you solve x-y=3 and x-2y=3?

Aug 5, 2015

Subtract one of the given equations from the other to get
$\textcolor{w h i t e}{\text{XXXX}}$$y = 0$
then substitute back into either of the equations to get
$\textcolor{w h i t e}{\text{XXXX}}$$x = 3$

#### Explanation:

[1]$\textcolor{w h i t e}{\text{XXXX}}$$x - y = 3$
[2]$\textcolor{w h i t e}{\text{XXXX}}$$x - 2 y = 3$

Subtract [2] from [1]
[3]$\textcolor{w h i t e}{\text{XXXX}}$$y = 0$

Substitute $0$ for $y$ in [1]
[4]$\textcolor{w h i t e}{\text{XXXX}}$$x - 0 = 3$
[5]$\textcolor{w h i t e}{\text{XXXX}}$$x = 3$