Computer Archeticture course

A computer uses memory words of 24 bits each. it has the follwing registers : PC AR TR AC DR and IR. It needs 130 memory reference instructions. All instructions have op code part and address part. there is no indirect bit.

a) how many bits needed for the op code part and address part.

b) what is the maximum size of the memory

c) indicate the size of each register of the following registers : PC AC AR TR DR IR

i cannot solve this question and i really appreciate all the help i can get :) thanks in advance