Whereas negative (-) odds tell you what you have to bet on the favorite to winR$100, positive (+) odds tell you how much you'll win for everyR$100 you wager on the underdog. So, a team with odds of +120 would payoutR$120 for everyR$100 wager.
So, a bettor looking to winR$100 will riskR$180, while a bettor looking to winR$50 would wagerR$90. Remember the amount you wager remains with the sportsbook if your side loses, while a winning bet returns your winnings and initial investment.