Answer:
Suppose we have a total of 16 drummers.
for the first pattern we have 2 drummers in each row, this means that we have a total of 16/2 = 8 rows.
Now, for the second pattern, we have 4 times as many in each row, so we have 4*2 = 8 drummers in each row, then we have 16/8 = 2 rows.
You can see that in each pattern we have the same number of drummers, but a different number of rows.
Now, we only can do this if the total number of drummers is a multiple of 8 (because in the second part we want 8 drummers in each row, so if we want that the numbers of rows to be a whole number, then we must have that the total number of drummers is a multiple of 8)
