Alberto uses the steps below to solve the equation One-half x minus 3 equals 7. Step 1: One-half x minus 3 plus 3 equals 7 plus 3

Step 2: One-half x plus 0 equals 10

Step 3: One-half x equals 0

Step 4: 2 (one-half) x equals 2 (10)

Step 5: 1 x equals 20

Step 6: x equals 20

Which justifies Step 6 of his work?

the addition property of equality
the identity property of addition
the multiplication property of equality
the identity property of multiplication