An ore contains 25% of an alloy that has 90% iron. Other than this, in remaining 75% of the ore ,there is no iron. How many kgs of the ore are needed to obtain 60 kg. of pure iron.?  Choose one:
A) 266.69	B) 266.67	C) 266.66	D) 263.66	E) 266.61

Rationale: "explanation : let us take 100 x kgs of ore . now it contains 25 x kgs of alloy and it contains 90 % ( 25 x ) kgs of iron . 90 % ( 25 x ) = 60 kg ⇒ x = 60 × 10090 × 12560 × 10090 × 125 = 8383 so iron ore required = 100 × 8383 = 266.66 answer : d"
Answer: D