# How do you solve the following linear system: #-7x - 5y =4, -x + y = 21 #?

##### 1 Answer

Nov 14, 2015

#### Answer:

#### Explanation:

We start with:

There are three ways of solving these problems. I'll choose substitution, as I find it easier. Let's start. First of all, we leave

We now substitute this into the other equation:

We now substitute this into any of the equation. I'll choose the second one: