### Easy Addition and Easy Subtraction Word Problems

All Easy Addition and Easy Subtraction word problems involve three sets.

Suppose that set A consists of 3 boys. (The number 3 is called an addend.)

Suppose that set B consists of 2 girls. (The number 2 is also an addend.)

(It is important that these first two sets A and B have no members in common.)

The third set is the set that consists of the members of A together with the members of B – in this case the 5 children. Let’s call that set C.

(The set C is called the union of A and B. The number 5 is called the sum.)

We can make up word problems involving the sets A, B, and their union C in three different ways. However, as you will see below, one of those problems is an example of Easy Addition while two of them are examples of Easy Subtraction.

1. Suppose that there are 3 boys in the playground and 2 girls in the playground. How many children are in the playground altogether? (This is an example of Easy Addition. The number of elements in A (3 boys) and the number of elements in B (2 girls) are both given. The problem is to find the number of elements in C (the 5 children). The corresponding equation is 3 + 2 = □.)

2. Suppose that there are 5 children in the playground. Suppose that 2 of those children are girls. How many of those children are boys? (This is an example of Easy Subtraction. The number of elements in B (2 girls) is given and the number of elements in C is given (the 5 children altogether). The problem is to find the number of elements in A (the 3 boys). The corresponding equation is
5 – 2 = □.)

3. Suppose that there are 5 children in the playground. Suppose that 3 of those children are boys. How many of those children are girls? (This is also an example of Easy Subtraction. The number of elements in A (3 boys) is given and the number of elements in C is given (the 5 children altogether). The problem is to find the number of elements in B (the 2 girls). The corresponding equation is 5 – 3 = □.)

 set A set B set C - their union Easy Addition given given find Easy Subtraction* find given given Easy Subtraction* given find given

*It is important to notice that the two subtraction problems are not identical, but that they are both examples of Easy Subtraction.

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