A boy purchased (bought) a party-length sandwich 51 in. long. He wants to cut it into three pieces so that the middle piece is 6 in. longer than the shortest piece and the shortest piece is 9 in. shorter than the longest piece. How long should the three pieces be?
The shortest piece has a length of ______ in.
Middle piece has a length of _______ in.
Longest piece has a length of ______ in.