$$16 + 9 = 25$$  $$25 + 25 =50$$  $$50 + 50 =100$$ 
There is a piece of wire. First, half of the piece is used. Then, half of the remaining piece is used. Next, $$16$$ meters are used. Finally, $$9$$ meters are left. The original piece of the wire is~\uline{~~~~~~~~~~}~meters long. 
Options:
(a) $$36$$ 
(b) $$50$$ 
(c) $$64$$ 
(d) $$100$$ 