What you can win:
£5 bet on Arsenal returns £35. £5 bet on West Ham returns £200. You will get paid in cash at the normal odds and then your balance will be topped up to reflect the price boost in the way of free bets. e.g. bet £5 on West Ham and if they win, you get paid in cash at the normal odds of 5/1 (£25 return) and the other £175 comes as free bets.