I know this is a very easy problem, but I'm having a hard time getting my head around this concept, consider this example from a book.
*Jerry bought a pie and ate 1⁄5 of it. Then his wife Doreen ate 1⁄6 of what was left. How much of the total pie was left?
To solve this problem, begin by jotting down what the first sentence tells you: Jerry =1/5
Doreen ate part of what was left, so write a word equation that tells you how much of the pie was left after Jerry was finished. He started with a whole pie, so subtract his portion from 1:
Pie left after Jerry = 1 - 1/5 = 4/5
Next, Doreen ate 1⁄6 of this amount. Rewrite the word of as multiplication and solve as follows. This answer tells you how much of the whole pie Doreen ate: Doreen = 1/6 * 4/5 = 4/30*
Now what I don't understand is the part where 1/6 is multiplied into 4/5 when it should, the book says that in almost all fraction word problems the word "of" almost always means "multiplication" and that it still means that way even when it comes to dividing fractions.
Can anybody explain to me the fraction rules and how they work in word problems?