Pitt Jones Company, a manufacturer of small appliances, 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) $30,000 20,000 lines
Account verification (accounts) $15,000 20,000 accounts
Correspondence (letters) $10,000 1,000 letters

The above activities are carried out at two of its regional offices.

Northeast Office Midwest Office
Account inquiry (hours) 100 hours 200 hours
Account billing (lines) 10,000 lines 7,000 lines
Account verification (accounts) 1,000 accounts 600 accounts
Correspondence (letters) 50 letters 100 letters

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