how many kg of pure salt must be added to 100 kg of 10 % solution of salt and water to increase it to a 25 % solution ?
"amount salt in 100 kg solution = 10 * 100 / 100 = 10 kg let x kg of pure salt be added then ( 10 + x ) / ( 100 + x ) = 25 / 100 40 + 4 x = 100 + x 3 x = 60 x = 20 answer is d"
divide(subtract(25, 10), subtract(const_1, divide(25, 100)))