I can solve this for X and Y if I put in numeric values for a,b,c,d,e,f,r,s,z, but I would like to solve for X, Y analytically. Is it possible? The restrictions are: a,b,c,d,e,f,r,s,z,s,X,Y are all positive real numbers, and a>X>Y>b>0.
soln = Solve[{
-(a - X)/c + (X - Y)/e + s^2*X*(X - Y)/(r + f) -
0.5*s^2*f*(X - Y)^2/(r + f)^2 ==
0 , (Y - b)/d - (X - Y)/e - s^2*Y*(X - Y)/(r + f) -
0.5*s^2*f*(X - Y)^2/(r + f)^2 == 0
}, {X, Y}]