Question

How do you solve by substitution `x = y - 1` and `y = 4 - 2x`?

Answer 1

`{x=y-1`
`{y=4-2x`
Substitute for `x` into the second equation:
`y=4-2(y-1)`
`y=4-2y+2`
`3y=6`
`y=2`
Back into the first equation:
`x=2-1=1`
Solution
`x=1`
`y=2`