Added 2, multiplied by 3, subtracted 6 then divided by 4 to give an answer of 6. what was the starting number?

6 is final 'answer'

you divided 4, so you must multiply 4 now

6 x 4 = 24

you subtracted 6, so you must add 6

24 + 6 = 30

you multiplied 3, so you must divide 3 now

30/3 = 10

you added 2, so you must subtract 2 

10 - 2 = 8

8 is your starting number

work backwards

hope this helps

The right answer is option d.

Iam unsure about what the proof is, therefore as much as wish to i can not.