The steps below show the incomplete solution to find the value of q for the equation 4q − 2q − 4 = −1 + 21:

Step 1: 4q − 2q − 4 = −1 + 21
Step 2: 4q − 2q − 4 = 20
Step 3: 2q − 4 = 20

Which of these is most likely the next step?