I’m how many different ways can she give the four remaining flowers to the rest of the teachers in the afternoon

can you ask the question more clearly

It is the first choice.

Step-by-step explanation:

This is a sequence where

the next term is obtained by adding 6.

first term = -9 + 6(0) = -9

second term = -9 + 6(1) = -3

third term = -9 + 6(2) = 3

4th term = -9 + 6(3)  = 9  

and 81 = -9 + (6*15).

So the answer is  Sigma (-9 + 6n)  from n= 0 to n = 15.