Question

Algebra 1. Please show work.

Answer 1

Try this:
Given:
$\left \{ {{x-y=1} \ [1] \atop {x+y=3} \ [2]} \right.$
1) [1]+[2]: 2x=2 ⇒ x=2
2) [2]-[1]: 2y=1 ⇒ y=1.
3) answer: (2;1)