Question

How do you solve the simultaneous equations `2x + y = 12` and `x + y = 7`?

Answer 1

`x=5,y=2`

Explanation:

Make `y` the subject in one equation:

`2x+y=12` => `y=12-2x`

Substitute into the second equation and solve for `x`:

`x+y=7` => `x+12-2x=7` => `x=5`

Use this value to solve for `y`:

`x+y=7` => `5+y=7` => `y=2`