Answer:
Correct option: C.
(Both Joey and Nolan)
Explanation:
The step Joey did is:
Add 7x to both sides of the equation
Then, he got:
13x - 42 + 7x = 18 - 7x + 7x
20x - 42 = 18
The step Nolan did is:
Add 42 to both sides of the equation
Then, he got:
13x - 42 + 42 = 18 - 7x + 42
13x = 60 - 7x
So both of them used correctly the addition property of equality in the first step of their work.
Correct option: C.