John want to buy a $100 Trouser at the store, but he think itâ€™s too expensive. Finally, it goes on sale for $70. What is the percent decrease?  Choose the correct option
A) 20 % B) 30 % C) 40 % D) 50 % E) 60 %

Rationale: "the is always the difference between our starting and ending points . in this case , it â € ™ s 100 â € “ 70 = 30 . the â € œ original â €  is our starting point ; in this case , it â € ™ s 100 . ( 30 / 100 ) * 100 = ( 0.3 ) * 100 = 30 % . b"
Answer: B