40 L of water was poured into an empty container, after which 20% of the container remained unfilled.

40 L of water was poured into an empty container, after which 20% of the container remained unfilled. How much water should be added to the container to fill it?

The unknown number of liters of water, which is 20% of the total volume of the tank, is denoted by the letter X.

If the entire volume of the container is 100%, then 40 liters will be:

100% – 20% = 80% of the total capacity.

The unknown number of liters of water, which is 20% of the total volume of the tank, is denoted by the letter X.

We make up the proportion and determine the unknown amount of liters of water:

40 liters – make up 80% of the total volume of the container;

X liters – make up 20% of the total;

X = 40 liters * 20% / 80% = 10 liters.

Answer: you need to top up with 10 liters of water.