Bronze is an alloy of tin and copper. What percentage of the alloy is copper in a piece

Bronze is an alloy of tin and copper. What percentage of the alloy is copper in a piece of bronze consisting of 6 kg of tin and 34 kg of copper?

First you need to find the mass of a piece of bronze, since it is an alloy of copper and tin, then you need to do the following:
1) 6 + 34 = 40 (kilogram) mass of bronze
Next, you need to find out what weight one percent of the bronze has:
2) 40/100 = 0.4 (kilogram) weight of one percent of bronze
Now let’s find out what is the content of copper and tin in bronze:
3) 6 / 0.4 = 15 (%) tin content in bronze
4) 34 / 0.4 = 85 (%) copper content in bronze