The answer is B, 7.6-(-1.7)=9.3
So, here we have an exponential function.
Remember that an exponential function has the form:

Where a represents an initial amount, and r is the rate of this amount to change. (Increase, or decrease).
So, given that the population of City A in 2000 was 40 thousand people and the population increased by 13% each year, we can say that

So,

For city B:

But something different happens with city C. This is not an exponential function, this is a linear function.
So,

Answer:
Trying to solve this leads to an absurdity, so No Solution.
Step-by-step explanation:
5x+12=5x−7
Lets attempt to solve:
Subtract 5x from both sides
5x - 5x + 12 = 5x - 5x - 7
0 + 12 = 0 - 7
12 = -7
This is absurd so there is no solution.
You hit the woah with a song on