Question

How do you solve the system of equations: `y=3x -10` and `x= 12- 4y`?

Answer 1

Re-write the equations in the form
`ay + bx = c`
then solve as normal.

`y = 3x -10` becomes
`y-3x = -10` (equation 1)

`x= 12 -4y` becomes
`4y + x = 12` (equation 2)

Multiply equation 1 by 4, giving
`4y-12x = -40` and subtract from equation 2

`13x = 52`
`rarr x = 4`

Substituting back in any of the earlier equations gives
`y = 2`