Jack, Jenny, and Tony have 18 flowers total. Jack has 5 flowers, and Jenny has 10 flowers. How many flowers does Tony have?

3
5
10
18

Since Jack has 5 flowers and Jenny has 10, Tony must have 18 - 5 - 10 = <<18-5-10=3>>3 flowers. Answer: \boxed{3}.

To find out how many flowers Tony has, we can subtract the number of flowers Jack and Jenny have from the total number of flowers.

Total number of flowers = 18
Number of flowers Jack has = 5
Number of flowers Jenny has = 10

To find the number of flowers Tony has, we subtract the sum of Jack and Jenny's flowers from the total number of flowers:

Tony's flowers = Total number of flowers − (Jack's flowers + Jenny's flowers)
= 18 − (5 + 10)
= 18 − 15
= 3

Therefore, Tony has 3 flowers.