c6 is the invoice
c7 is the actual occurence
c8 (the actual cost of a job) = c6/c7
and c9 is a constant number (a rate)

What I wanted in C10 was the amount of gain or loss. In the 3rd
column, we gave $100 credit of work to 5 people, considering that it
cost $22 everytime, I wanted to calculate it so that we lost $110
instead. I couldn't figure it out... too many parameters.

thanks... and you're not daft... I just didn't explain myself