Question

And it's elimination using addition and subtraction x-y=1 x+y=3

Answer 1

Get one x+y=3 to y=x+3 and plug it into x-y=1 and you get x-(x+3)=1. Destitute the x and solve. Once you get what x equals plug it to to either equation for the value of x and solve for y

Answer 2

X-y=1. ....> x=1+y
(1+y)+y =3
1+y+y =3
1+2y =3
2y=3-1=2 ....>y =2/2=1
Y=1
X-y=1
X-1=1. ....>x=1+1 =2

X=2. Y=1