What is 20 less than 40? In this problem, the terminology "less than" is telling the reader to subtract 20 from 40, written as 40 -- 20. In this type of problem, it is important for the child to remember to take the first number from the second number.
What is 100 minus 1? In this problem, the terminology "minus" is telling the reader to subtract 1 from 100, written as 100 --1. The term minus is one of the first subtraction words taught to children, and is one of the most often used.
The terminology "take away" can be used in two ways. First, what is 10 take away 3? This tells the reader to subtract 3 from 10, written as 10 -- 3. A second way to use this terminology is to say, "Take away 3 from 10." Once again, this tells the reader to subtract 3 from 10, written as 10 -- 3. Quite often, this problem will be presented to young children in story format such as, "I have 10 apples. Three were taken away. How many do I have left?"
What is the difference between 4 and 5? This terminology is asking the reader to subtract the smaller number from the larger number. This problem could also be stated as, "What is the difference between 5 and 4?" or "Find the difference between the following numbers: 5, 4." No matter how it is stated, the problem is written and solved as 5 -- 4.
What is 15 decreased by 7? This terminology tells the reader to subtract 7 from 15. In this type of problem, the second and smaller number is always subtracted from the first and larger number. It is written as 15 -- 7. Another way to state this problem is, "Decrease 15 by 7."