I have got a couple of fiqures, the total time spent doing somthing,

format (h):mm

And the number of things done

but when i try to calculate the number of things done per hour, it dosent
work.

the caluculation should work out to be

51 (things)
20:31:44 (hours) - (shown on excel as 20:31 due to my formating)
should equal 2.49 per hour
but the calculation comes to 59.62??????

Please help