Alberto uses the steps below to solve the equation.

1/2x - 3 = 7

Step 1: 1/2x - 3 + 3 = 7 + 3

Step 2: 1/2x + 0 = 10

Step 3: 1/2x = 10

Step 4: 2 (1/2) x = 2 (10)

Step 5: 1x = 20

Step 6: x = 20

Which justifies Step 6 of his work?

1. the addition property of equality

2. the identity property of addition

3. the multiplication property of equality

4. the identity property of multiplication

4. the identity property of multiplication

Step-by-step explanation:

From Step 5 to Step 6, the equation changes from 1x = 20 to x = 20. The only difference is that the x term is written as "x" instead of "1x."

The identity property of multiplication states that multiplying any number by 1 results in the original number; this means that 1x, multiplying x by 1, is the same as x.

I think that would be option 4. (its common sense really!)