You have $15 and admission is $5, so you know have $10 before doing any games. If you wanted to play 12 games, you would need $10.20, which you do not have. But, if you wanted to play 11 games, then you would need $9.35, which is just under $10.
So the maximum amount of games that you could play would be 11 games.
Because there are only two things you can do with these two " family" members. 81 divided by 9 is 9. 9 times 9 is 81. Strictly speaking, there should be three in the family: 9,9 and 81 9 is the square root of 81. 81 is the 9 squared.
