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

Answer:
No. Of slices my friend eats = No. Of slices eaten by me - No. Of slices my friend eats fewer than me
= 5 - 2
= 3
Hope this helps!
It’s similar to D because they are going to have the same measured angle
Answer:
x² + y² = 100
6² + 8² = 100
36 + 64 = 100
100 = 100
Because this is a true statement, the answer is yes, it does lie on the circle.