Answer:
C. He added 15 to both sides in step 3.
Step-by-step explanation:
In order to isolate the b term, Jolon should subtract 15 to both sides in step 3, as follows:
Step 1: -2=3(5)+b
Step 2: -2=15+b
Step 3: -2-15=15-15+b
Step 4: -17=b
Step 5: y=3x - 17