Hi

I have a formula that works but trying to change it need help.

My current formula is 

=IF(ISERROR(IF(H25<G25,(1+H25)-G25,H25-G25)*24)=TRUE,0,IF(H25<G25,(1+H25)-G25,H25-G25)*24)
it calculates hours worked ie user enter 6:00 in g25 and 14:00 in h25 it will produce 8hr.

What i want to do is -0.5 to produce 7.5hr worked.

I did this by -0.5 in red below. it worked BUT when there is no hours it shows -0.5 i want it to show 0 only.

=IF(ISERROR(IF(H25<G25,(1+H25)-G25,H25-G25)*24)=TRUE,0,IF(H25<G25,(1+H25)-G25,H25-G25)*24-0.5)
Can some help me.