Top Baller - NBA promotion

Did anyone else get the NBA promotion email yesterday? It says "Simply bet a minimum of £20 on 10 Basketball 'moneyline' markets between now and Sunday 2nd December and we'll give you £10 cashback*!" The t&c's describe it as "you need to place a minimum £20 worth of bets (matched) on the Betfair Exchange on each of ten Basketball 'Moneyline' markets during the promotional period."

Is this 10 £20 bets then, or 10 £2 bets which therefore total £20? Clarification please. Thanks