human
Nancy can hula hoop for 10 minutes. Casey can hula hoop 3 minutes less than Nancy. Morgan can hula hoop three times as long as Casey. How long can Morgan hula hoop?
assistant
How long can Casey hula hoop? ** Casey can hula hoop 3 minutes less than Nancy so she can hula hoop for 10-3 = <<10-3=7>>7 minutes
How long can Morgan hula hoop? ** Morgan can hula hoop three times as long as Casey, who can hula hoop for 7 minutes, so she can hula hoop for 3*7 = <<3*7=21>>21 minutes
#### 21