California

Solution

Abby had 5 treats left.
Carter had 6 treats left.
Scott had 4 treats left.
Tracey had 3 treats left.

Explanation

Abby's dog did 5 tricks.

	10 to start
−	5 tricks done
5 treats left

Scott's dog did 6 tricks. (Abby's + 1 = 6 tricks)

	10 to start
−	6 tricks done
4 treats left

Carter's dog did 4 tricks. (Scott's - 2 = 4 tricks)

	10 to start
−	4 tricks done
6 treats left

Tracey's dog did 5 tricks. (Carter's + 3 = 7 tricks)

	10 to start
−	7 tricks done
3 treats left