Question

How do you solve the system x=-4y and 3x+2y=20?

Answer 1

You may substitute `-4y` for every `x` in the second equation

Explanation:

`3*(-4y)+2y=20->-12y+2y=20`
`-10y=20->y=-2`

Now reverse the substitution to find `x`
`x=-4y=-4*(-2)=8`

Just to make sure, you can plug these values in the 2nd:
`3x+2y=3*8+2*(-2)=24-4=20` Check!