Once because if you subtract 10 from 100 you will have 90 left and if subtract 10 again that won't be subtracting 10 from 100.
3 men go into the hotel the rent a room and the clerk says it cost 30 dollars each man pays 10 dollars. The men go to there hotel room and the clerk remembers that it costs 25 dollars he sends his bell boy to pay the back he didn't know how to split the 5 dollars evenly with the 3 men so he payed he man a dollar and keep 2 dollars. This means each man payed 9 bucks right (cause they got one dollar back) so if you do 3 times 9 you get 27 dollars which is him much the payed all together right. But now add the 2 dollars that the bell boy kept that equals 29dollars what's happening!!!!!
In the next chapter there is not going to be a answer to this because there isn't.
(I get it now after like a hour of doing stuff it's very confusing)
