Find Points in The Cube

Question

In the cube $ABCDA'B'C'D'$, we have $3\overrightarrow{AM}=\overrightarrow{MD}$ and $2\overrightarrow{D'N}=\overrightarrow{NB'}$.

Find the points $M$ and $N$ in the cube;

So, i can't find a way to discover these points. Every method I've tried ended up with something illogical.

Answer 1

$3\overrightarrow{AM}=\overrightarrow{MA}+\overrightarrow{AD}$ so that $\overrightarrow{AM}=\frac{1}{4}\overrightarrow{AD}$.

In the same way $\overrightarrow{D'N}=\frac{1}{3}\overrightarrow{D'B'}$