X+y=45
X-y=17 let's make this equation x= form
X+y=45
X=y+17
Plug in x into first equation
Y+17+y=45
2y+17=45
2y=28
Y=14
Plug into any equation to figure out x
X+y=45
X+14=45
X=31
Y=14 and x=31
You can check if these are right by plugging into the other equation
X-y=17
31-14=17
17=17
The numbers are correct:) hope that helps