Could you be so kind to help me with that:

Most of credit card issuers use average daily balance (ADB) to calculate Finance Charge (FC). There are two ways:
1)average daily balance method, including new purchases;
2)average daily balance method, excluding new purchases;
The question is how to calculate the Finance Charge using both ways described above.
Specifications of the Card:
Grace Period(GP) = 0 days.
APR = 18.4%
No of Days in a Billing Cycle (BC)=30

Previous Balance =1051.93$
day1/06-day 16/06 : No activity
day 17/06 : purchase = 257.53$ payment=0
day 18/06-28/06 : No activity
day 29/06 payment=600$
day 30: No activity

According to the bank the charge of credit card for this period is 29.34, but how they arrived to this amount. Thats the question.
Thank you