Question 61576
I know when dividing fractions the second set you flip and then it becomes multiplication. But what if you have three sets??

8/21 / (-4/7) / 4/3

It all depends on how you group the fractions.
Let's look at a simple example: 40/2/5
If you do 40/2 first and then divide by 5 you get 20/5 = 4.
If you do 2/5 first then divide that into 40 you get {{{40/(2/5) = 40*(5/2) = 100}}}.

In general, if you have {{{(a/b)/c}}} then multiply numerator (a/b) and denominator (c) by 1/c to get {{{(1/c)(a/b) = a/(bc)}}}.

If you have {{{a/(b/c)}}} then multiply numerator (a) and denominator (b/c) by c/b to get {{{a(c/b) = ac/b}}}.

So, see if you can now do the problem. Let me know if you can't.