Purchased 10 bicycles for $5,000, paying $2,400 down and agreeing to pay the rest in 30 days. Iam confused with question

What is confusing? Price - down payment / 30 =cost for day or /7 =cost per week. Are you sure that is the whole question?
This is not accounting, it is simple math.

Assuming you are studying accounting, a wild assumption. This would seem to be part of a multiple part question, the question might be asking you for the journal entries to record the transaction. Accounts like inventory, creditors, cash come to mind. One of the requirements of accounting is precision, another is clarity neither of these appear to be present in this question

Looks like a journal entry. There will be 3 accounts with your debits and credits equaling $5,000