how many liters of water must be evaporated from 50 liters of a 8 - percent sugar solution to get a 10 - percent solution ?
"8 % of a 50 liter solution is 4 l which is 10 % of the solution at the end . the solution at the end must be 40 l . we need to evaporate 10 liters . the answer is b ."
subtract(50, multiply(divide(50, const_100), 10))