In a mixture of cement and sand weighing 30 kg, cement is 60% p. How much sand should

In a mixture of cement and sand weighing 30 kg, cement is 60% p. How much sand should be added to make the cement 40%?

To begin with, let’s find how many kilograms are the mass of sand in a 60 percent mixture with cement.

In the initial data for this task, it is reported that the mass of this mixture is 3 tens of kilograms.

Therefore, the mass of sand is 30 – (60/100) * 30 = 30 – (6/10) * 30 = 30 – 18 = 12 kg.

Let x denote the desired mass of the added sand.

Then we can make the following equation:

(x + 12) / (30 + x) = 60/100,

solving which, we get:

(x + 12) / (30 + x) = 3/5;

5 * (x + 12) = 3 * (30 + x);

5x + 60 = 90 + 3x;

5x – 3x = 90 – 60;

2x = 30;

x = 15.

Answer: you need to add 15 kg of sand.