What kind of equation do I use to solve these two problems?

Payment

$200.00

04/15

Charge

Gas $26.37

04/22

Charge Macy's

$105.42

04/25

Charge Starbuck's

$4.24

She started the month with a balance of $342.57.

1. Find the average daily balance.

2.If her card charges an 18.5% annual interest rate on heraverage daily

balance, calculate Miss Pepper Mill's finance charge for the month of April.