The total mass of the three pieces of granite is 156 kg. A piece of gray granite is 18 kg heavier than a piece

The total mass of the three pieces of granite is 156 kg. A piece of gray granite is 18 kg heavier than a piece of red granite, and a piece of red granite is 15 kg lighter than a piece of white granite. Find the mass of a piece of red granite. Find and write down the mass of the other two pieces of granite.

Let’s solve this problem using the equation.
Let the mass of red granite be x kilogram, and the mass of gray granite (x + 18) kilograms, then the mass of white granite (x + 15) kilograms. We know that the total mass of the three pieces of granite is 156 kilograms. Let’s make the equation:
x + x + 18 + x + 15 = 156;
x + x + x + 18 + 15 = 156;
x + x + x + 33 = 156;
x + x + x = 156 – 33;
x + x + x = 123;
x * (1 + 1 + 1) = 123;
x * 3 = 123;
x = 123: 3;
x = 41 kilograms – the mass of red granite;
41 + 18 = 59 kilograms – the mass of gray granite;
41 + 15 = 56 kilograms – the mass of white granite.
Answer: 41 kilograms; 59 kilograms; 56 kilograms.