How many kg of pure salt must be added to 100kg of 10% solution of salt and water to increase it to a 12% solution? Choose the correct choice from the following answers.
A) 6.7	B) 2.3	C) 9.6	D) 12.5	E) 7.9

Rationale: "amount salt in 100 kg solution = 10 * 100 / 100 = 10 kg let x kg of pure salt be added then ( 10 + x ) / ( 100 + x ) = 12 / 100 250 + 25 x = 300 + 3 x 22 x = 50 x = 2.3 answer is b"
Answer: B