John want to buy a $100 Trouser at the store, but he think it’s too expensive. Finally, it goes on sale for $10. What is the percent decrease? Choose the correct choice from the following:
A) 90 %
B) 30 %
C) 40 %
D) 70 %
E) 80 %

Rationale: "the is always the difference between our starting and ending points . in this case , it ’ s 100 – 10 = 90 . the “ original ” is our starting point ; in this case , it ’ s 100 . ( 90 / 100 ) * 100 = ( 0.9 ) * 100 = 90 % . a"
Answer: A