tom had 18 comic books , while Diane and Helen had none. Tom gave 1/3 of the comic books to Diane who passed 1/3 of these books along to Helen. If Tom then gave Helen 1/3 of the books he had left, how many comic books did Helen receive from Tom and Diane

As the books are distributed, we have the following quantities

T:18 D:0 H:0
T:12 D:6 H:0
T:12 D:4 H:2
T:8 D:4 H:6