C Company, a manufacturer of electronics, had the following activities, allocated costs, and allocation bases:

Activities	Allocated Costs	Allocation Base
Account inquiry (hours)	$60,000	2,000 hours
Account billing (lines)	$100,000	20,000 lines
Account verification (accounts)	$15,000	30,000 accounts
Correspondence (letters)	$10,000	1,000 letters

What is the cost per line for the account billing activity?