Question

How do I substitut 3x+y=2, 4×+y=20?

Answer 1

`(x,y)=(18, -52)`

Explanation:

`3x+y=2` => `y=2-3x`
`4x+y=20`
`4x+2-3x=20`
`x=18`
`y=2-54=-52`
`(x,y)=(18, -52)`

Answer 2

`y=-52`
`x=18`

Explanation:

Since `y` is a constant in both equations, you can shift `3x` in `3x+y=2`, so `y=2-3x`.
Then you can just substitute into `4x+y=20`
So `4x+(2-3x)=20`
`x+2=20`
`x=18`
Then substitute into any equation `x=18`
Substituting into first equation,
`y=2-3(18)`
`y=-52`