Skill 6B
Basic Algebra: Related Addition and Subtraction Facts
Here, we want to see if the student understands the word "related" when used in math problems, and in this case, related means that when changing operations from plus to minus or minus to plus, that all three numbers can be used but in a different order to get a correct answer.
For example, 5 + 2 = 7 is related to 7 - 2 = 5.  See how both problems use the same numbers?
All that has changed is that the operation has gone from plus to minus and the order of the numbers has changed as well. Since both problems use the same numbers but in a different order they are therefore related. Understanding this concept helps when the student will be using addition to "check" the answer of a subtraction problem and vice-versa.

Add or subtract as the problem asks. 
Two of the math facts are related - which are they?

2 + 9 = 11 - 9 = 11 - 4 =