DE or systems of DEs can only be solved numerically
You have to use a solve block or one of the standalone solvers (which I guess are also available in the full version only).
I added an arbitrary initial condition and I had to change the first equation as Prime choked on the one you provided. Not sure why but I guess that not both equations are allowed to include derivations of both functions. So I multiplied the first by 2 and subtracted the equations to get a new equivalent equation.
You don't necessarily need to use a solve block, if you're willing to do some math. But your problem description is not complete as Leopold also pointed out: initial conditions are missing.
It's very well possible that both solutions are equal. This first solution, with X0=0 and Y0=10, leads to:
Success!
Luc
