. The first shelf has x books on it, the second shelf has twice as many books as the 29 first shelf and the number of books on the third shelf is the first and second shelf
combined. There are a total of 72 books. How many books are on each shelf?

This law is sometimes called the grouping property. as you can see, regardless of how the numbers are grouped, the answer is still 13. the associative law of multiplication is similar to the same law for addition. it says that no matter how you group numbers you are multiplying together, you will get the same answer.