Cash out formula 3-Way market

[rosunad]

Hi everyone,

I am finishing an application and need to implement a CashOut button. While it is easy to apply when there is only one bet I can't find anything about when I have several positions closed on different options in the same market, an example:

Home Win:
Odd: 2.00 Stake 5 - Back
Odd: 2.3 Stake 2 - Back

Draw Win:
Odd: 3 Stake 5 - Lay
Odd 2.9 Stake 2 - Back

If the current positions were:

Home -> Back 2.4 Lay 2.45
Draw -> Back 2.7 Lay 2.72
Away -> Back 3 Lay 3.05

How could I calculate the current cash out?

Thank you in advance