Question

How do you solve `3x - y = 9` and `2x + y = 6`?

Answer 1

I fond:
`x=3`
`y=0`

Explanation:

You can add the two equations (in columns):
`{3x-y=9`
`{2x+y=6`

`5x+0=15`
So:
`x=15/5=3`
substitute this back into the first equation:
`3*3-y=9`
`9-y=9`
`y=0`