Question

How do you solve this system of equations: `a+ b = 4 and a - b = 10`?

Answer 1

`a=7` and `b=-3`

Explanation:

If `a+b=4` and we subtract `b` from both sides, we get `a=4-b`

`a-b=10`
Since we know that `a=4-b`, we can substitute `a` with that.
`4-b-b=10->`
`4-2b=10`

Subtract `4` from both sides:
`-2b=10-4->`
`-2b=6`

Divide both sides by `-2`

`(-2b)/(-2)=6/(-2)->`
`b=-3`

Since we know `a=4-b` and `b=-3`, `a=4-(-3)` which is equal to `a=7`.