Question

There are two alloys consisting of zinc, copper and tin. The first alloy contains 25% zinc and the second alloy contains 50% copper. The percentage of tin in the first alloy is twice that in the second alloy. 200 kg of the first alloy and 300 kg of the second are melted together. The new alloy contains 28% tin. How many kg of copper are there in the new alloy?

Answer 1

z1 = 50 kg

c2 = 150 kg

t1 = 4/3 t2

4/3 t2 + t2 = 140 kg ... 7/3 t2 = 140
... t2 = 60 kg ... t1 = 80 kg

c1 = 200 kg - 50 kg - 80 kg = 70 kg

c1 + c2 = 220 kg