I have inherited a workbook from a previous employee and cannot understand
the following formula.

=IF(AND(((AA22-INT(AA22))=0.59),((AA22-INT(AA22))<=0.61)),
(AA22+0.4),AA22)

The worksheet is used to work out hours&mins of a working day and in this
case cell AA is 2hrs 59 mins and the above formula returns 2.99. Can someone
explain?
Thanks