A very logical problem. 1. The problem statement, all variables and given/known data x5y=3z and x3y=z2-3z-2 so what is (z)xy 2. Relevant equations No equations, just multiplication,division etc. 3. The attempt at a solution let xy=a a^5=3z we can write this as a^15=(3z)^3 a^3=z^2-3z-2 also this a^15=(z^2-3z-2) and then equalize but I don't think I will get something, isn't it?