If the numerator of a fraction be increased by 20% and its denominator be diminished by 10%, the value of the fraction is 20/21. Find the original fraction ?  Pick
A) 1 / 2	B) 3 / 5	C) 4 / 7	D) 5 / 7	E) 7 / 9

Rationale: "let the original fraction be x / y then , 120 % of x / 90 % of y = 20 / 21 120 x / 90 y = 20 / 21 x / y = 5 / 7 answer is d"
Answer: D