A recursive formula for the sequence 18 9 4.5

Could somebody me with this radical simplification?

The equation represents the function f, and the graph represents the function g. f(x)=3(5/2)^x determine the relationship between the growth factors of f and g. a. the growth factor of g is twice the growth factor of f. b. the growth factor of f is twice the growth factor of g. c. the growth factor of f is 2.5 times the growth factor of g. d. the growth factor of f is the same as the growth factor of g.

In which month was the peak, the largest deposit, made? january june july august