Is this exponential growth or decay y=⅓e^x​

Successful implementation of a new system is based on three independent modules. module 1 works properly with probability 0.96. for modules 2 and 3, these probabilities equal 0.95 and 0.90. compute the probability that at least one of these three modules fails to work properly.

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Ineed with math stuff it involves graphs