no. of elements in $\mathbb Z[i]/\langle 3+i\rangle$. $\mathbb Z[i]/\langle 3+i\rangle$ can be represented as :$\{a+3b+\langle 3+i\rangle\big|~~a,b\in \mathbb Z\}$
How shall I find the total no. of elements in $\mathbb Z[i]/\langle 3+i\rangle$..  
please provide some hint how should I proceed?   

Hint : $3 = -i$ in the given ring
