jmc

We can represent the amount of gold with $g$ and the amount of chests with $c$. We can use the problem to make the following equations: $$9c-18=g$$ $$6c+3=g$$ We do this because for 9 chests there are 2 empty and if 9 were in each 9 multiplied by 2 is 18 left. Therefore, $6c+3=9c-18.$ This implies that $c=7.$ We therefore have $g=45.$ So, our answer is $\boxed{45}$.