5. What part of substitution into a formula do you not understand?
You are given ...
.. A = 5000
.. r = 4
.. n = 10
Conveniently, you are asked for V(10).

6. The x-axis is a horizontal asymptote of any exponential function. The function value is as close to zero as you like, but is never zero. The range of the function does not include zero.