So if 5 friends bought one ticket each which was $8 a ticket means that they spent $40 alone on tickets. But you know that they spent $62.50 all together as a group. So with that being said to find out how much they spent all together as a group on popcorn you want to subtract $62.50 From $40.00. Which equals $22.50. But to find out how much they spent separately on one bag each you want to divide $22.50 by 5 to get the answer you are looking for which is $4.50 on one small bag of popcorn each. I hope i helped!