Plotting function two functions which is parametric of two symbolic variables?

ya =
 
- (5*r^2*s)/4 + (5*r^2)/4 - (5*r*s^2)/4 + (5*r)/4 + (5*s^2)/4 + (15*s)/4
xa =
 
- (15*r^2*s)/4 + (5*r^2)/4 - (15*r*s^2)/4 + (25*r)/4 + (5*s^2)/4 + (15*s)/4 + 5

The above are part of my code. I want to plat the above two functions like xa vs ya, but the problem in they are further functions of two symbolic variables r and s.

I tried using fplot but there i can use two functions which is function of only one variable. Could anyone suggest if there is any other way to accomplish this?

Thanks!!!!