You are given the data points (t, r) = (0, 1) and (t, r) = (5, 6), where "r" has the units "millions per hour". What is the slope of the line through these points? What then is the equation of that line?
Once you have the line equation, plug "2" in for "t" to find the answer to part (a).
For part (b), I don't know if you have learned anything more complex than shown above. If not, just do the computations by hand: At t = 0, you have 5 millions (m) and know that 1 m will be added. This means that t = 1 starts with 5 + 1 = 6 m, and you know (from your equation) how many will be added. Continue until you have found the required total value.
For part (c), you can find the values of r for each value of t, and then do the "sum and divide" thing to find the average value.
If you get stuck, please reply showing your work and reasoning so far. Thank you!