slang 2: a piece of cake

Alice    : Hi guy! What's up?
Austin  : I'm not doing well.
Alice    : Tell me why?
Austin  : I can't follow regional football match on Saturday cuz I have to keep 
             my Dad's shop.  
Alice    : It's a piece of cake. I can replace ya if you don't mind.
Austin  : For real? Thanks a bunch for your help.
Alice    : Never mind Bud.