Say the odds of Chelsea winning the Premiership are 3, or 2/1. These are the odds of them winning at the bookmakers. To lay at the exchange Chelsea winning the Premiership the odds are the same, 3.
If you placed £10 on Chelsea to win the satta matka at the bookmakers, and then lay £10 at the Exchange, both outcomes will have cancelled each other out.
If Chelsea win the Premiership, then you get £30 from the Bookmakers (£20 profit, and the £10 bet is returned with the winnings.) With the lay at the Exchange, you will have to pay out £30 (Their £10 stake and the £20 winnings from the bet). Therefore you would have £20 profit at the Bookmakers, and £20 loss at the Exchange. This means you are back to square one, and have neither gained nor made a loss.
Just to confirm, had Chelsea not won the Premiership, then you would have lost your £10 bet at the Bookmakers, but you would have won the £10 lay at the Exchange, again cancelling each other out.
All of this is of course pretty pointless, unless you were using a free bet.
An Example of a Matched Bet using your own money and a free bet:
We will use the same scenario as before to keep things simple.
The odds of Chelsea winning the Premiership are 3, or 2/1. These are the odds of them winning at the bookmakers. To lay at the exchange Chelsea winning the Premiership the odds are the same, 3.
If you used a free bet stake of £10 on Chelsea to win the Premiership at the Bookmakers, and then lay £10 (your own money) at the Exchange, then no matter what happens you will have made a profit.
If Chelsea win the Premiership, then you have won £30 (as long as the free bet was stake-returned). You would then have to pay out £20 at the Exchange for the lay. This means that you have an overall profit of £10 (£30 winnings minus £20 lay loss).
If Chelsea don’t win the Premiership, then you have lost your free-bet (no actual loss though as it didn’t cost you anything) but you will win your £10 lay, so you will have £10 profit.
From this scenario, you can see that by using a free bet you can guarantee to gain nearly almost of the free-bet amount back. There are a few issues that mean its not always possible to extract the full amount back. At the Lay Exchanges they often charge commission on any winnings on a bet or lay. At the most popular Exchange, Betfair, the commission is usually %5.
Another issue is that sometimes the free-bet is SNR or Stake Non-Returned. This means that if you were to place a £10 bet on odds of 3 (2/1), you will only receive £20 back, and your stake isn’t returned.