Answer: On Tuesday, Marietta sold more part of boxes of cheese.
Explanation:
Since we have given that
Part of boxes of cheese Marietta sold on Monday is given by

Part of boxes of cheese Marietta sold on Tuesday is given by

Now, to compare the both the part of cheese, we need to make the denominator same ,
L.C.M. of 9 and 20 = 180
So, it becomes,

Similarly,

Hence, On Tuesday, Marietta sold more part of boxes of cheese.