Green-up at different offsets

Hi,
Can't work out the equations for the back bet odds

I want to lay and then hedge out in stages (Attempt greenup)

e.g. lay at 5.0 for £100
Then place 3 back bets, at differing odds, to green out for a profit
a back bet for £47.50 to give profit of £2.50 (5% of £50)
a back bet for £27.00 to give profit of £3 (10% of £30)
a back bet for £18.50 to give profit of £2.50 (12.5% of £20)

Please point me in the right direction.

Hello!

Here is a complete list of green-up formulae:

10 Facts About Green-up in MarketFeeder Pro