1. The problem statement, all variables and given/known data Piece of quartz containing gold weights 102,5g and average density is 7,98g/cm3. Density of quartz is 2,65g/cm3. How much does gold weight? 2. Relevant equations ρ=m/V avg.ρ= m1+m2/V1+V2 3. The attempt at a solution Using average density I find that volume of this piece is 12,84cm3. ρ=m/V ⇒ V=m/ρ V=102,5/7,98=12,84 Now using formula for calculating average density(avg.ρ= m1+m2/V1+V2) I get that 7,98=m1+m2/12,84. Now 102,5=m1+m2 ⇒m1=102,5-m2 so I place this into the formula. 7,98=(102,5-m2)+m2/12,84 but now -m2 and +m2 cancel each other off and I can't seem to find what to do now. Can you please help?