smc

Let $a$ be first and $b$ be second. We can then get equations based on our knowledge: $b-a=9-b$ and $b/a=a/3$. We then get $b=(9+a)/2$ from our first equation and we substitute that into the second to get $\frac{9+a}{2a}=a/3$ which simplifies to $2a^2-3a-27=0$ which be $(2a-9)(a+3)=0$ and $a=9/2$. Then $b=27/4$. Their sum is $\boxed{11\frac{1}{4}}$.