Question

How do you solve the system of equations `x= - 4` and `- 8x - 5y = - 18` by using substitution?

Answer 1

Y is equal to 10. For how, see the explanation.

Explanation:

Substitute `x` with `-4` in the second equation.
This gets you:
`-8(-4) - 5y = -18`
Multiply `-8` and `-4`:
`32 - 5y = -18`
Subtract 32 from both sides:
`-5y = -50`
Divide both sides by negative five:
`y = 10`
You don't need to find x, since it's already given.
There are other ways to solve this with substitution, involving adding or subtracting different things in a different order, but they all end up with the same answer.