Answer:
Whole numbers or integers from 0 to 10
Step-by-step explanation:
Either 0 tickets can be sold, or 1, or 2, or 3, or 4, etc. up to a maximum of 10;
It is not possible to sell -1 tickets or ¹/₂ a ticket and we are told they don't sell more than 10 so 11 is not a possibility either;
Logically then, the only possibilities are whole numbers between 0 and 10
