Convert time cell into a decimal cell leaving values exact.

Here's my excel example

Date
1-Jan Thu
In
4:12 PM
Out
7:03 PM
In
7:20 PM
Out
12:03 AM
Exceptions
Regular
7:51
Lunch
0:17
Total
7:34

My solution I'm looking for is taking cell J4 "7:34" and making it show up as 7.34 in cell K4.

or alternatively, since I'm working on a payroll time sheet. I would like for some way, formula or otherwise to give me an absolute accurate value of 7 hours and 34 minutes, rolling over every 60 minutes to the next hour, any additional time that's added on properly when the "Total" cells are summed up for the total hours worked.

Right now what I'm getting is a percentage based on the overall hours for that period of time; using formula "=(J14-INT(J14))*24" in cell K4; which gives me 7.57 for the value in cell K4.

The problem with this is when you're dealing with time and money, this method overcompensates by .31 hour/minutes, making the dollar value based on the "excel interpretation of calculating the percentage of minutes of an hour" time, inaccurate.

The actual value of hours worked would be, for example, 84 hours and 46 minutes.

The excel summed up time with the formula above, equals 84.77 and the value I want in another cell that totals all the hours up should equal exactly 84.46.

Any ideas? thanks in advance.