Some water was evaporated from 400 g of a 12% solution and a 16% solution was obtained.

Some water was evaporated from 400 g of a 12% solution and a 16% solution was obtained. How much water did you evaporate?

1. According to the condition of the problem, 400 grams of a 12% solution are given.

12% is 12/100 of the total substance.

So the substance was only 400 * 12/100 = 48 grams.

2. During evaporation, the amount of water decreased, but the amount of the substance remained unchanged.

Let X grams of water evaporate.

Then the weight of the solution was (400 – X) grams.

The result is 16% or 16/100 of the substance.

3. We get an equation with one unknown.

48 / (400 – X) = 16/100.

16 * (400 – X) = 48 * 100.

400 – X = 300.

X = 100 grams – water.

Answer: A total of 100 grams of water was evaporated.