Abby,Brandon,Cedric,andDeirdreareplanningtoattendaconcert.IftheirfriendKimalsogoeswiththem,theywillgetagroupdiscountontheirtickets.Ifthetotalpriceoftheticketswiththegroupdiscountisthesameasthetotalpriceoftheticketswithoutthegroupdiscount,howmuchisthediscount? A: 5％ B: 10％ C: 20％ D: 25％ E: 33％