In identity element of addition, you have to remember that a number plus zero will always equal to the number you add to zero. Example would be 3+0=3.
In Equality property of addition, is when you add same number to both sides that will make both equation equal. Example: 4=4, 4-2= 4-2= 2. In additive inverse property, is when you need to think of a negative number to add to another number so it will equal to 0. The number you need think is the opposite of the possitve number you have. Example: 4+(-4)= 0 and (-4)+ 4= 0.
Hope that you'll understand it.
