Question: An open economy IS-LM model

Consider the following model of an open economy          Y- C(Y) - X(e) = C

                                                                                                                  L(Y,r) = M

                                                                                                          X(e) + F(r) = 0

The first equation is the IS equation which state that investment equals savings; the second equation is the LM equation stating that the demand for money is equal to the supply of money; finally the third equation is the balance of payment equations which state that net exports (expports minus import) equals to the net inflow of foreign capital.

Given the signs of the partial derivatives are:

   0< C' < 1                                   X_Y < C                                             I', L_r < 0

a) Analyse the effect of an expansionary monetary policy on national income (Y) and the exchange rate (e), i.e. find the partial derivatives dY/dM and de/dM and the determine their signs if possible.

b) Suppose now that net export depend on both income and the exchange rate. That is, the net export function takes the form

        X = X(Y,e)                       X_Y < C                    and             X_e > C

Do the implications of the model remain the same? That is, do the partial derivetives dY/dM and de/dM have the signs as in part (a).

Pls help 2 solve this question...