I have a problem with a spreadsheet

Total Logged in Time Not Ready Time Percentage Worked
5.3 .27 8%
6.3 1.5

My Spreadsheet consists of the above figures, I need to first convert the time 5.3 to 330 minutes and then .27 to 27 minutes and then get the percentage of Not Ready Time to Total Logged in time. My only other problem is the Not Ready Column is not always under 1hr.
I am wondering if I will need two other colums to convert the Total Logged In Time and the Not Ready Time to minutes or if I can get one big formula in the Percentage worked column that converts the time in both columns and then gives me a percentage.

Your help on this would be greatly appreciated.

Thanks from Jeda