### solving system of equations

I'm trying to solve a system of equations, but somehow Sage does not solve for it. I have solved similar systems of equations before using the same methods, but somehow it is not working this time around. What is causing Sage to not solve this?

```
var('r,B,a,y,k,d,c,N,A,theta')
h=solve([r==B*(a*(y/k)+1-d), y==c+k*(r-1+d), (1-a)*(y/N)==((1-theta)/theta)*(c/(1-N)), y==A*k^a*N^(1-a)],y,c,N,k)
show(h)
```