Stray cats loved eating goldfish in the pond leaving w goldfish. Paige had raised x goldfish in the pond initially. How many goldfish disappeared?
Let's say that the number of goldfish that disappeared is $x$. 

Then, the number of goldfish that Paige had raised initially is $x+y$, where $y$ is the number of goldfish that are left in the pond. 

We are told that $y=x-5$. 

We can plug this value of $y$ into our equation for $x+y$ to solve for $x$: 

$$x+y=x-(5-x)=2x-5$$

We can solve this equation for $x$: 

$$2x-5=x+y$$
$$2x=x+y+5$$
$$2x=y+10$$
$$x=y+5$$

We are told that $y=x-5$, so we can plug this value of $y$ into our equation for $x$: 

$$x=x-5+5$$
$$x=2x-5$$
$$0=x-5$$
$$x=5$$

Therefore, the number of goldfish that disappeared is 5.