Question

-7x + 4y = 24
4x - 4y = 0
solve by substitution - please add explanation and work

Answer 1

(-8, -8)

Explanation:

You need to solve one of the equation for x or y. I am going to solve the bottom equation for x

4x -4y = 0 Add 4y to both sides

4x = 4y Divide both sides by 4

x = y Substitute y in for x in the first equation

-7x + 4y = 24

-7y + 4y = 24 Combine like terms

-3y = 24 Divide both sides by -3

y = -8

Since x = y

x = -8

Check:

-7y + 4y = 24

-7(-8) + 4(-8) = 24

56 - 32 = 24

4x - 4y = 0

4(-8) - 4(-8) = 0

-32 + 32 = 0

0 = 0