To solve this question, let's say the unknown values are x.
Part 01:

To solve it, you can use the Identity property.
According to this property, adding 0 to a number does not change the number.
So,

Part 02:

To solve it, you can use the Commutative Property.
According to this property, changing the order of addends does not change the result.

Part 03:

To solve it, you can use the Associative Property.
According to this property, you can change the grouping of the addends without changing the result.
