Match each item in column a to an answer in column b. what property is shown by the equation? column a: 1. –(–33 + 18) = 33 + (–18) 2. –10 + (–15) = –15 + (–10) 3. 4 + (29 + 16) = 4 + (16 + 29) 4. –12 + (12 + 27) = (–12 + 12) + 27 column b: a. commutative property b. associative property c. opposite of a sum property