I'm really struggling with this one. I know the answer (it's in the back of the book) but I can't see how they get to the answer at all.

<sorry, the display is wrong, the '2' '3' and '4''s are supposed to be powers>

Simplify:

a2b*ac2/b2c

2c 2b 2a

This obviously equals:

a2b*ac2*2a

2c 2b b2c

The answer in the book is:

b3

ac

and I don't get how the 'a' got to the bottom of this.

My answer always ends up something like:

a4

b2