Which equation illustrates the commutative property of addition?
12+6+15=12+15+6
12+6+15=12+(15+6)
12+6+15=18+15
12+6+15=12+6+15
12+6+15=12+15+6
12+6+15=12+(15+6)
12+6+15=18+15
12+6+15=12+6+15