He has 5 bows. Add one set of 2bows and 20 shirts and add them untill you reach 40. (4 bows, 40 shirts) Then, to make 50 you add 10 so divide 20 by 2 and then 2/2 and you get 1 bow and 10 shirts. Add all that together and you get 5 bows and 50 shirts.