I would have thought something along the lines of 14.75 = 14.45
so ignore the hours and we are left with mins 60 *75/100 old maths here
the long way of doing this is 60/1 * 75/100 or 50 /100 for 30 mins however you might end up with some funny times so if some one put in 14.13 you would get
60 *13/100 = 7.80 mins the .8 mins would be 60*80/100 seconds = 48 seconds - recommend you use whole numbers on this element
old school math
hoe this helps