Question

How do you solve the system `4x+8y= -20` and `7x-3y= -1`?

Answer 1

Substitution

Explanation:

`4x+8y = -20` --- 1
`7x-3y` = -1--- 2
Multiply equation 1 by 7 and equation 2 by 4.
`28x+56y = -140`
`28x-12y` = -4
Make `28x` the subject,
`28x= -140-56y`
`28x= -4+12y`
Equate the equations,
`-140-56y = -4+12y`
`-136 = 68y`
`y = -2`