ANSWER:
Amount terry was charged in interest for the billing cycle is $ 4.9 approximately.
SOLUTION:
Given, Terry has a credit card that uses the average daily balance method for the first 18 days of one of his billing cycles, his balance was $350, and for the last 12 days of the billing cycle, his balance was $520.
His credit cards APR is 14%
Using the average daily balance method, the amount to be used in calculating Theresa's interest is given by:

Therefore, the interest charge on Theresa for the biling cycle is given by:

hence, amount terry was charged in interest for the billing cycle is $ 4.9 approximately.