9514 1404 393
Answer:
every 6th day
Step-by-step explanation:
Mary will have a painting class on the same day as every 3rd dance class. That's the same day as every 2nd painting class. Mary has the two classes together on every 6th day.
[tex]\texttt{- 1 2 3 4 5 6 1 2 3 4 5 6}\\\texttt{d - d - d - d - d - d - d}\\\texttt{p - - p - - p - - p - - p}[/tex]
