# How do you solve x + y = 4 and 9x + 9y = 36?

Apr 14, 2016

$y = 4 - x$ for any $x \in \mathbb{R}$

#### Explanation:

These two equations both describe the same line. Any point on the line is a solution, so there are an infinite number of solutions.

For example, given any $x \in \mathbb{R}$, let $y = 4 - x$.

graph{x+y=4 [-10, 10, -1.72, 8.28]}