NEED HELP ASAP pt 2

[twins12]

The product of two numbers is 15. Express the sum of the squares of the two numbers as a function of a single variable .
Answer_______________

 

[JuicyBurger]

\(\displaystyle x*y = 15 \ and \ x^2 + y^2 = G\)

Where G is just the sum of the squares, as shown.

Now how can you rewrite X and plug it into the second equation to get only Ys?