John want to buy a $100 Trouser at the store, but he think it’s too expensive. Finally, it goes on sale for $50. What is the percent decrease?	Choose the correct option:
A) 20 %  B) 30 %  C) 50 %  D) 70 %  E) 80 %

Rationale: "the is always the difference between our starting and ending points . in this case , it ’ s 100 – 50 = 50 . the “ original ” is our starting point ; in this case , it ’ s 100 . ( 50 / 100 ) * 100 = ( 0.5 ) * 100 = 50 % . c"
Answer: C