formula for elapsed time with condition

Hi - I need help on a forumla for calculating hours worked with 1/2 hour lunch/break automatically subtracted. For every 5 hours of work, a 1/2 hour break needs to be subtracted. I'm thinking that would be >=5.5 hours is the key time.

A9 is TIME IN and B9 is TIME OUT.

The formula that I'm using is this: =IF(B9-A9>=0.2291685,B9-A9-0.0208335,B9-A9)*24

This formula works for hours worked up to and including 5 as well as over 5.5, but when an ee works 5.5 hours, it should subtract that 1/2 hour and return 5 hours, but I can't get it to do that. I have tried moving around the conditons with no success. I hope I've been clear. Thanks in advance for any help.

Do you mean =IF((B9-A9)*24>=5.50,(B9-A9)*24-0.5,(B9-A9)*24) ?

Yea! thank you so much - both of those formulas work well, except for the 2nd 5.5 hour period, an additional 1/2 is not subtracted. We have ee's that sometimes work over 11 and 12 hours during harvest, so it's necessary to have a full hour subtracted if they work over 11 hours.

Thank you, daddylonglegs. This will save me considerable time and effort. Blessings upon you and your day.