My Question is :

Let G=(a b , c d) such that a,b,c,d belongs to Z(3)={0,1,2} and

det(G)=ad-bc not equal to 0

Show that order of G=48

In fact I know that order of a finite group is equal to order of generator of it. i.e if G is cyclic group generated by a, then the order of a is same as the order of G, namely the smallest positive integer such that a^k=e

But it seems that this will not be helpful here. How should I start in order to proof that this group is of order 48

Thank you in advance