The price of fuel may increase due to demand and due to overproduction. marco is studying the change in the price of two types of fuel, a and b, over time.

the price f(x) = 2.15(0.98)^x

part a: is the price of fuel a increasing or decreasing and by what percentage per month? justify your answer.
part b: the table below shows the price g(m), in dollars, of fuel b after m months.

graph below
m (number of months) 1 2 3 4
g(m) (price in dollars) 4.19 3.98 3.78 3.59