Final answer:
Dan's possible numbers of additional miles are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
Step-by-step explanation:
To find the possible numbers of additional miles Dan will run, we need to subtract the miles he has already run from the maximum number of miles he plans to run. Dan has already run 20 miles and plans to run at most 29 miles. So the possible numbers of additional miles he will run are:
Answer: A) 0, 1, 2, 3, 4, 5, 6, 7, 8, 9