Stella 1 box = Michael 4 boxes
If Stella moves 10 boxes, how many boxes Michael can move?
[tex]\begin{gathered} \frac{1box}{10box}=\frac{4box}{x} \\ x=\frac{4}{1}\cdot10=40\text{ boxes} \end{gathered}[/tex]Therefore, Michael will move 40 boxes at the time Stella moves 10.