It's a little hard to tell what is intended here. Your text may offer examples that you can follow.
5. (4/5) / (1/5) = 4
6. 1/2 = 3/6
... 2/3 = 4/6
7. (3/4) / (1/8) = 6
or perhaps
... (3/4) / 6 = 1/8
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The idea of any diagram of this sort is to help you understand the relationship between various fractions and the different ways they can be represented. IMO, the "division sentence" itself is not the important thing. Rather, the important thing is understanding what you get when you multiply or divide fractions in various ways.
If you have that part figured out, the appropriate form for the "division sentence" can be found in an example in your text. (If not, the text needs work, and your teacher should be consulted.)
When you expand the equation in the bracket you'll find out that you'll get a^6 + 4a^4 + !6a^2 - 4a^4 - 16a^2 -64. then your final result will be a^6 - 64 <span />
