According to the statement, you have that 6 tickets for the price of each ticket is equal to $174 and from that, you can determine the price of each ticket:
6*P=174
P= price of each ticket
P= 174/6= 29
Now, as it says that one of Henry's friends gives him two $20 bills, that means that he gives him $40 and you have to subtract the price of the ticket from that:
40-29= 11
The answer is that if one of Henry's friends gives him two $20 bills, Henry has to return $11.
