# Sylvanite is a mineral that contains 28.0% gold by mass. How much sylvanite would you need to dig up to obtain 66.0 g of gold?

You need to dig up $236 \cdot g$ of mineral...
And of course, 236*gxx28.0%=66*g...
Of course, if you got such a rich gold ore....I would not stop at digging up just $236 \cdot g$. I think I could move $10 \cdot {m}^{3}$ a day (well I bet I could when I was younger!)...and I would keep working....