Answer:
<h2>There are 30 possible combinations of picking two letters.</h2>
Step-by-step explanation:
The combinations are defined as
Where 
is the total number of elements and 
is the number of letter we are gonna picke, which is two. Using this information, we have
Therefore, there are 30 possible combinations of picking two letters.
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)
The answer is 75. What I did to get my answer is divide 15 by 0.20
