The alloy of copper, tin and lead weighs 105kg. At the same time, copper in the alloy is 15 kg less

The alloy of copper, tin and lead weighs 105kg. At the same time, copper in the alloy is 15 kg less than tin, and lead is 2.5 times more than copper. How many kilograms of lead does the alloy contain?

1. If the mass of copper in the alloy is e, then the mass of tin is 15 + e kg, and the mass of lead is 2.5 e kg. The alloy weighs 105 kg, then we make an equation by adding the masses of metals in the alloy:
e + 15 + e + 2.5 e = 105,
4.5e = 105 – 15,
4.5e = 90,
e = 90 / 4.5,
e = 20 kg.
2. Let’s calculate the mass of lead in the alloy:
20 * 2.5 = 50 kg.
Answer: the alloy contains 50 kg of lead.