Given the following:

29 day billing cycle
4/17 billing date previous balance $1,100
4/27 payment 700
4/29 charge 300
5/7 payment 60

the average daily balance is:
$910.34
$755.17
$810.43
$755.71
none of these

4/17 Billing date previous balance $1,100
4/27 Payment 700
4/29 Charge 300
5/7 Payment 60

 Day      action                balance       # of days with that balance

4/17                                     1,100          from 4/17 to 4/26 = 10 days

4/27     payment 700          400           from 4/26 to 4/28 = 2 days 

4/29     charge 300             100            from 4/29 to 4/7 = 8 days

5/7      charge                       60            from 5/7 to 5/16 = 9 days

5/16     none                         -                -

Weighted average: [1,100*10 + 400*2 + 100*8 + 60*9] / 29 = 13140 / 29 = 435.10

435.10