Problema Solution

Brass is an alloy composed of 55% copper and 45% zinc by weight. You have 25 ounces of copper. How many ounces of zinc do you need to make brass?

Answer provided by our tutors

Assuming that all 25 ounces of copper are used first we will find the weight of the brass.

Let 'x' represent the weight of the brass.

55% of x is 25 means:

0.55x = 25 divide both sides by 0.55

x = 25/0.55

The weight of the zinc is 45% of 25/0.55 or:

0.45*(25/0.55) = 20.45 ounces 

20.45 ounces of zinc are needed to make brass.