Many thanks for taking time out to try to help me.
"However, something about your question doesn't make sense.
You said these 2 things:
b12 is entered as an amount ie £0.75
b12 value from a formula is 10"
Sorry for confusion I should of course said that c12 was the cell containing the formula. In other words the value 15 is the result of the formula k12*1.75 that sits in the c12 cell.
Hope this makes it better to understand.
In conditional formatting I can only see a condition where the value of a cell is a known quantity. I want to enter a value in k12 which sends a calculated result to c12 which is then compared to b12 to see which is the greater amount.
Difficult to explain without showing whole spreadsheet.
Any further help appreciated.