Problem:

Tell what property is illustrated in each equation below.

       1.   3 + 5 + 7 = 7 + 5 + 3

       2.   (3 + 5) + 7 = 7 + (3 + 5)

       3.   (3 + 5) + 7 = 3 + (5 + 7)

       4.   3(5 + 7) = 3 ´ 5 + 3 ´ 7