Question

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

Answer 1

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

Answer 2

Answer:

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.