How are odds calculated and possible return calculated?

Odds are generated based on favorites and underdog model. 

If you place a 1,000 Naira bet on a 2.5 odds market. 

Your possible return is 1,000 x 2.5. 

Your possible return is 2,500 Naira. 

If you select multiple bets in an accumulator and your total odds is 25

Possible return will be your stake 1,000 x 25 which is 25,000