sum of ages

Let $M$ be the present age of Marvin and $A$ be the present age of Ana. Then we have

$\dfrac{M}{A}=\dfrac{1}{3}$ $\color{#D61F06}\implies$ $A=3M$ $\color{#3D99F6}(1)$

and

$A-2=6+M-2$ $\color{#D61F06}\implies$ $A=6+M$ $\color{#3D99F6}(2)$

Substitute $\color{#3D99F6}(2)$ in $\color{#3D99F6}(1)$ , we have

$6+M=3M$

$6=2M$

$M=3$

Solving for $A$ , we have

$A=3(3)=9$

It follows that the sum of their ages twenty years from now is $9+20+3+20=\boxed{52}$ .