The time in minutes until the next bus departs a major bus depot follows a distribution with f(x)=1/20 where x…

The time in minutes until the next bus departs a major bus depot follows a distribution with f(x)=1/20 where x goes from 25-45 minutes.
a.whats the random variable? X=?
c. graph the probability distribution. someone please explain how
to do this?
g.find the probability that the time is at most 30 minutes. Sketch and label a graph of the distribution. shade the area of interest. write answer in a probability statement. How do i graph this? and is the probability statement P(x<30) i.P(25