Comparative subtraction compares two different quantities. A real-world example of comparative subtraction deals with ages: If Mr. Smith is 54 years old and Mrs. Jones is 49 years old, how much older is Mr. Smith than Mrs. Jones? The student subtracts 49 from 54 to get the answer -- five years.
The additive property of subtraction teaches subtraction as the inverse of addition. The additive property compares two different quantities by showing the relationship between the smaller quantity and the larger quantity through addition. For example, how many eggs need to be added to a batch of six eggs to reach a dozen?
The subset principle of subtraction is based on the idea that by subtracting a part from a whole, the answer is the remaining part. For example: If there are 10 cupcakes on a platter and David eats two of them, how many cupcakes remain?
Similar to the subset principle, the take-away principle examines the difference between the whole and the subset. For example, if Jason drove 200 miles and Molly drove 140 miles, how much farther did Jason drive than Molly?