9 friends brought 178 tickets How many more ticket would they have to buy for all of them could have

9 friends brought 178 tickets How many more ticket would they have to buy for all of them could have the same amount?

If we take 178 mod 9 to find the remainder, we get 7.

If we buy the 7 more (remainder) tickets, we have:
9 friends - 7 remainder = 2 tickets

To prove our work, we add the 2 tickets + 178 tickets = 180 tickets
180 tickets / 9 friends = 20 tickets per friends

So our answer is 2 tickets