From the initial 77 bottles, she receives 15 full bottles (with 2 spare empties). From the 17 empties, she receives 3 more full bottles (with 2 spare empties). From the 5 empties she receives one final full bottle.
In this long division, each number has been replaced by another. The answer has also been removed. Can you determine the answer?
Hint: Try breaking each cog size into prime factors.
Answer: 25 revolutions.