Number of kids is 5 and number of adults is 3.
Step-by-step explanation:
    Cost of tickets for kids = 3(8-x) = 24 - 3x
    Total cost = 33 = 6x + 24 - 3x = 3x + 24
⇒ 3x = 9
∴ x = 3
⇒ 8 - x = 8 - 3 = 5
∴ Number of kids is 5 and number of adults is 3.