Question

If x-y=10 and x squared-y squared =40 then y=?

Answer 1

12 I know I gave you the wrong answer

Answer 2

Solve for y in the first equation
-y=-x+10
y=x-10

Now substitute y in the second equation
x^2-(x-10)^2=40
x^2-(x^2-20x+100)=40
20x-100=40
20x=140
x=7

Plug the value of 7 in to any of the equations
7-y=10
y=(-3)

Final answer: y= -3