a cell that applies different levels of discount???

Hello again, its been a while.....

Ive come across a problem formula I just cant seem to work out, I have attached the work book for others to see.

what I need is a cell that when I type in a number it subtracts that number as as percentage in the relevant cells.

so in this workbook the cell is: F27 (I need to be able to add a discount from 1%-100%)

and I want the discount to be applied to any figure in the following cells G25 to S25 (with out changing the number in them)

and then what discount that was applied to cells G27 to S27

with the discounted figure populated in the following cells G31 to S31

i hope that makes sense..... ive tries to google with no luck at all....