A tradesman sold an article at a loss of 10%. If the selling price had been increased by $50, there would have been a gain of 10%. What was the cost price of the article ? Choose the correct choice from the following
A) $ 150
B) $ 200
C) $ 250
D) $ 120
E) $ 100

Rationale: "let c . p . be $ x then 110 % of x - 90 % of x = 50 20 % of x = 50 x / 5 = 50 x = 250 answer is c"
Answer: C