The Sylow Theorems · Hard problem

In $GL(2,\mathbb Z_3)$ (order $48$), the normalizer of a Sylow $3$-subgroup (the subgroup of upper-triangular matrices with $1$'s on the diagonal) has order $12$. How many Sylow $3$-subgroups does $GL(2,\mathbb Z_3)$ have?