I just need help with this question:
An alloy has copper and zinc in the ratio of 11 : 7.
If 12 Kg of Copper has been used in making the alloy, what is the total weight of the alloy.

Here if we use 11 Kg of Copper and 7 Kg of Zinc, total weight of alloy formed is 18 Kg.
Hence we can create a ratio between the weight of copper and the weight of alloy which is 11 : 18.
So if 1 Kg of copper is used, the weight of the alloy will be 18 / 11 Kg.
Hence for 12 Kg of copper, it will be (18/11) x 12 = 19.63 Kg.