Jenny has nine marbles, but her best friend Susie gives her ten more! However, the neighborhood bully, Danny, steals four marble
s from her. Jenny's marbles are all of very high quality, so she trades each of her marbles for three of John's marbles apiece. The very next day is Jenny's birthday so she receives seven marbles from her parents, and finally gives two to her sister. How many marbles does she have now?
