Percentage Profit formula

Hi,

What is the formula for creating a lay trigger to green up ?

The MFP green-up function creates x% profit of the original bet amount. But what if you want to create x% profit of the potential total return.

Thanks,

Cyber

The only formulae of all kinds of green-up are:

[lay amount]*[lay price] = [back amount]*[back price]

Profit = [lay amount] - [back amount].