There are infinitely many possible solutions to this equation since there are infinitely many possible values for x and y that satisfy the equation.

However, we can find some specific solutions by solving for one variable in terms of the other.

Expanding the equation, we have:

xy + 4y - x - 4 = 13

Rearranging the terms, we get:

xy - x + 4y = 17

Now, let's solve for y in terms of x:

4y = 17 - xy + x

y = (17 - x)/(4 - x)

Similarly, we can solve for x in terms of y:

x = (17 - 4y)/(1 + y)

These equations give us the relationship between x and y that satisfy the original equation. By substituting different values for x or y, we can find specific solutions.