Question

If an alloy containing 30% zinc is mixed with a 55 % zinc alloy to get 800 pounds of 40% alloy, how much of each must be used?

Answer 1

Have a look if it makes sense...

Explanation:

I considered quantities of Zinc in each alloy and the final amount as:

Where `x` and `y` are the quantities in pounds of alloy 1 and 2.
Solving the system I got:
`x=4.8 "pounds"` of alloy 1
`y=3.2 "pounds"` of alloy 2