The model shows the addition expression 18 + 12.


(A model containing 3 rows of 6 orange squares and 3 rows of 4 blue squares)


One expression that is equivalent to this sum is _______. 1. 3 + 6 + 4 2. 3(6 + 4) 3. 3 + 6(4) 4. 3(6) + 4