Maria writes the expression below. 21 + 3 + 6 + 9 − 3 Which expression could be shown to be equivalent to Maria's expression based on the commutative property of addition? Immersive Reader (20 Points) 12( + 2) 3( + 3) + 3(7 + 2 − 1) 3 + 9 + 21 + 6 − 3 3(7 + + 2 + 3 − 1)