substitution word problem

Question

For this problem, I know how to solve it, but can't set it up. I have 

x+y=3000

0.70x+0.35y=(0.58)(300) but it's quite right. Thanks!

 

A silversmith has two alloys, one containing 70% silver and the other 40% silver. How much of each should be melted and combined to obtain 300 grams of an alloy containing 58% silver?
40% silver alloy _____? 
70% silver alloy _____?

Answer 1

This is correct.  The first equation represents the total number of grams.  The second equation represents the total amount of silver.

 

The set up is all good.

 

x = amount of grams of the 70% of silver

y = amount of grams of the 40% of silver

 

 

Now just solve.

Answer 2

x represents the amount of 70% silver

300 - x represents the amount of 40% silver

0.70(x) + 0.40(300 - x) = 0.58(300)