The way I went about this problem is I set Y=X-N and substituted all over the place
So if expanding on the last entry I got
E[X]-E[N] + (E[X(X-N)]-E[X]E[X-N])/(Var(x)) * (X-E[X])
After some rearranging
E[X]-E[N] +(E[X^2]-E[XN]+E[X]^2+E[X]E[N])/(E[X^2]+E[X]^2]) * (X-E[X])
E[X]-E[N] + (E[X^2]-E[X]^2)/(E[X^2]-E[X]^2) * (X-E[X])
E[X]-E[N] + (X-E[X])
Thats what i got so far you sould be able to plug in values assuming this is right..theres an example like in class btw
Do you use law of iterated expectation here?