Answer:
1. He added 5 instead of subtracted 5.
2. He should have subtracted 5.
3. 2 2/3
Step-by-step explanation:
3x+5=13
subtract 5 to both sides 3x=8
divide both sides by 3 x=8/3 or 2 2/3
3x + 5 =13 is the error