Question

Please I need the answer quickly

Answer 1

Well, for number 15, this is what I came up with, I hope it is what your teacher is looking for: 
So it starts out with 3 butterflies, and it doubles every minute: 
3x2 = 6  That is for the first minute 
6x2 = 12 That is for the second minute 
12x2 = 24 That is for the third minute 
24x2 = 48 That is for the fourth minute

So, It asks for using the power of 2 in your answer, that is what I came up with for part A. 

For part B I would say something like this: 

X represents the number of butterflies left. 
The equation, using the information above would be this:

48-7 = X
Then simplify, which would leave you with 41 butterflies. 

I hope this helps! :)