Question

How do you solve `4x+3y=-5` and `x-y=-3` using substitution?

Answer 1

`x=-2 and y = 1`

Explanation:

In this answer, I have subbed in for x. A solution that subbed in for y would be equally valid (and might be instructive for you to do to check you get the same answer!).

Rearrange the second equation to obtain:

`x = y - 3`

Sub this into the first expression:

`4(y-3) + 3y = -5`

`4y - 12 + 3y = -5`

`7y = 7 implies y = 1`

`x = y - 3 = 1 - 3 = -2`