Calculating Copper & Zinc Mass in Yellow Zinc Brass

[metalmagik]

Homework Statement

Brass is an alloy of copper and zinc. Varying the mass percentages of the two metals produces brasses with different properties. A brass called yellow zinc has high ductility and strength and is 34%-37% zinc by mass.
(a) Find the mass range (in g) of copper in 185 g of yellow zinc.
(b) What is the mass range (in g) of zinc in a sample of yellow zinc that contains 46.5 g of copper?

Homework Equations

No specific formulas

The Attempt at a Solution

I got part (a), This is what I did roughly
(185 g)(.34) = 62.9 g of zinc 185 g - 62.9 g = 122.1 g of copper
(185 g)(.37) = 68.45 g of zinc 185 g - 68.45 g = 116.55 g of copper

Mass range = 116.55 g - 122.1 g of copper

I think that's correct. Now I just have no idea how to do part (b), there is no mass range for copper, just one number, 46.5.

Any ideas? Thanks guys :)

 

[Borek]

If total is 100% and Zn is 34%-37%, how much is Cu?

 

[metalmagik]

Ah I see, I think I got it now. I work backwards using an average percentage and actual mass value to get the total mass of the yellow zinc. Thank you!