Answer:
Using the average daily balance method, the amount to be used in calculating Theresa's interest is given by:
\frac{350\times12+520\times19}{12+19} = \frac{4200+9880}{31} \\ \\ = \frac{14080}{31} =$454.19
Therefore, the interest charge on jerry for the biling cycle is given by:
\frac{454.19(0.14)}{12} = \frac{63.59}{12} \\ \\ =\365/0.19 *31