A family goes out to dinner, and their bill before tax costs $68. Tax is 7.5%. They give a tip of 20% of the bill, calculated after adding tax. What was the total cost of their dinner, after-tax, and tip?

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.

The expression -8/-4 has the same value as -18/-9.