Explanation:
for part a
initial means starting point and starting point is always 0
so the question means number of thousands of bacteria in 0 hours, your n being the number of hours. so in part a u will simply just put 0 as n in equation
2^(0+3)
2³=8 thousands of bacteria
in part b
2^(n+3) means total number of bacteria
2^(n-1) is number of groups
its asking for number of bacteria in each group
so u will simply divide number of bacteria by groups
its like u have 30 candies and there are 5 groups and they ask u to find number of candies in each group so u simply divide 30 by 5
so 2^(n+3)/2^(n-1)
base is same so powers will subtract since there is division sign
2^(n+3-(n-1))
2^(n+3-n+1)
2^(3+1)
2^4= 16 thousands of bacteria in each group