Answer:
The town's annual energy consumption will be of 6.57 trillons of BTU after 9 years.
Step-by-step explanation:
The annual energy consumption of the town where Camilla lives increases at a rate that is proportional at any time to the energy consumption at that time.
This means that the consumption after t years is given by the following differential equation:

In which k is the growth rate.
The solution is, applying separation of variables:

In which C(0) is the initial consumption.
The town consumed 4.4 trillion British thermal units (BTUs) initially.
This means that 
So


5.5 trillion BTUs annually after 5 years.
This means that
. We use this to find k. So








So

After 9 years?
This is C(9). So

The town's annual energy consumption will be of 6.57 trillons of BTU after 9 years.