are you going to show a picture??? its impossible to answer otherwize
Answer:
The step 4 is not what he should have done. But the wrong is step 5, because if he added -2x both sides, it would give the following equation:

and not 
Note that in step 4 he should have added 2x and not -2x to both sides, but we still have the equality. The problem is that step 5 is totally wrong.
I don't know what answer is expected to this question, but I would mark step 5, because this is mathematically wrong.
Solving the equation

Using distribution

Add
both sides


Add 12 both sides

Divide both sides by 5

9.42 is the circumference, for future refernce its just pi times diameter :)
Y=2/3x-3. Follow the formula y=Mx+b. M is the slope, and b is the y intercept.
Answer: 1+1 is equal to 2, because adding a singular object to a specified amount of something to the number 1, it will increase by just that. Therefore, if the quantity of something is one, adding the number one to its value will be the number 2.