Question

X + y = 12

Answer 1

X+y=12
x+y+-y=12+-y
x+y+-y=12+-y
x=-y+12

x-y=10
x-y+y=10+y
x=y+10

z^2=-y^2+22
x=(square root) -y^2+22 or x=-(square root) -y^2+22

Hope this helps!