maths for profit and loss

[Roadhouse]

Hi does anyone know excel formula to show the profit and loss like betfair does in red and green on different horses when you place a lot of different backs and lays. I would like to put it in a spreadsheet not linked to gruss.

[Captain Sensible]

They just do it on individual profit/losses on each runner, so you just calculate whatever the runners bets pnl is then take away the combined back bets and add the combined lay stakes of the other runners to get the pnl