In the following example of "Simplifying an Expression", what reason would be used for step B?

Simplify the expression 3k + 7 + 2k and justify each step

3k + 7 + 2k = 3k + 2k + 7 A
=( 3k + 2k )+ 7 B
= (3 + 2) k + 7 C
= 5k + 7 D
A. Addition
B. Commutative Property
C. Associative Property
D. Distributive Property

Question

In the following example of "Simplifying an Expression", what reason would be used for step B?

Simplify the expression 3k + 7 + 2k and justify each step

3k + 7 + 2k = 3k + 2k + 7         A
                    =( 3k + 2k )+ 7      B
                    = (3 + 2) k + 7       C
                    = 5k + 7                 D
 A. Addition
 B. Commutative Property
 C. Associative Property
 D. Distributive Property

anonymous · Answer

Which of the properties is concerned with grouping?

anonymous · Answer

Im sorry, im not sure what you mean.

anonymous · Answer

Well, in step A we had the sum ungrouped, and in step B it is grouped.  Which rule says that we can do that?