If you take 'x' as the number of chocolates you have, and you receive twice the number of chocolates from your friend, then what will be the number of chocolates you have in total?
3x
You have 'x' chocolates.
Since you get twice the number of chocolates from your friend='2x
So now, you will have thrice the number of chocolates you had initially.
Hence, the total number of chocolates you have will be equal to 3×x=3x