Exactly as in the question: 7+5 = 12
20
Commutativity of addition or the fact that addition is Abelian.
57
the number is 11
Exactly as in the question: 7+5 = 12
20
12.
9
Commutativity of addition or the fact that addition is Abelian.
57
the number is 11
12
5 x 7 and 6 x 7
Adding zero to any number exemplifies the identity property of addition. For example, 12 + 0 = 12 where adding zero does not change the sum.
Commutative Property of Addition
6+6=12, easy :D