SSC CHSL Model Paper 16

Copper : Aluminum = 7 : 4.
Let Copper and Aluminum in the weapon be 7x and 4x respectively.
Given, Aluminum in weapon = 12 kg
So, 4x = 12, x = 3
Copper = 7x = 7 × 3 = 21 Kg.
Total alloy in the weapon = 12 + 21 = 33 kg
But 12% alloy get destroyed in making the weapon, that is, 88% alloy is used in the weapon, so,
88 % alloy = 33 kg
100 % alloy = 37.5 kg