# How many kg of the first alloy and of the second alloy should be alloyed together to obtain 28 kgs of new alloy with equal contents of copper and zinc if in two alloys, ratios of copper to zinc are 5:2 and 3:4?

##### 1 Answer

Taking

1st alloy:

2nd alloy:

Together we will get

There are two conditions in this problem:

(a) combined weight should be

(b) amount copper and zinc must equal (that is,

Therefore, we have to solve the following system of two linear equations with two unknown:

Multiplying by 7 both equations:

Multiplying the first by 4 and the second by 3:

Subtract the second from the first:

Divide by 14:

Using the first equation in its original form and substituting

The answer: we have to take