Question: The ice cream parlor was offering a deal, buy 2 scoops of ice cream, get 1 scoop free.  Each scoop cost $1.50.  If Erin had  $6.00, how many scoops of ice cream should she buy?
Answer: 
Each scoop cost $1.50. If she buys 2, she gets one free. So it will cost her 2 * 1.50 = $3.00 for thee scoops total.
If you break it down, 3 scoops of ice cream cost $3.00 so 3/3 = $1.00 per scoop
Erin has $6.00 and each scoop ends up costing $1.00 each then 6/1 = 6 scoops total