Mr. Tip is working on the marching band's halftime show. During the first song, rows have 9 musicians each. During the second song, rows change to contain 6 musicians each. If there are a total of 252 musicians in the marching band, how many rows will there be when the musicians are in rows of 6 than when they are arranged in rows of 9?

Question

Mr. Tip is working on the marching band's halftime show.  During the first song, rows have 9 musicians each.  During the second song, rows change to contain 6 musicians each.  If there are a total of 252 musicians in the marching band, how many rows will there be when the musicians are in rows of 6 than when they are arranged in rows of 9?

At one point, while the musicians are changing from rows of 9 to rows of 6, there are 33 rows of musicians.  Some are in rows of 9.  The others are in rows of 6.  How many rows of 9 are there at this point in the performance?