# {x2−y2=55x−y=11 How can I find the value of y?

Solution:
Note that ${x}^{2}-{y}^{2}=\left(x-y\right)\left(x+y\right)$. Hence,

can be rewritten in the form

Adding the two equations, we obtain $2x=16$, and we conclude that $x=8$. Subtracting the two equations, we obtain $2y=-6$, and we conclude that $y=-3$.