Part A: "What is the y-intercept of the function? What does this tell you about the car?"
Well, the y-intercept is when the x-value is equal to 0. So find that, and that's your answer! I'll help you with the second question of part A. Basically, let's just say the y-intercept is y for now. The y-intercept, as I said before, is when the x-value is equal to zero. The x-value in this case represents time. And the y-value represents velocity. So that would mean that when 0 hours pass, the velocity is y mph. Now, the y-intercept should be really easy for you to find because it's like right there, but when you don;t have it in the graph, just plot the points at a website like wolframalpha or fooplot and look for where the line crosses the y-axis and that is your y-intercept.
Part B: Basically you're finding the slope. The slope formula is pretty simple and easy to calculate. m = (y2 - y1)/(x2 - x1). So you already know it's between x = 1 and x = 3, so just figure out the corresponding y-values, which are also on the table, plug them in, and calculate. Then you have the average rate of change, or slope.
Part C: This part I am not too sure, but I am assuming you have to make the y-value 60. and then figure out what the x-value would be. You can see by the pattern of the table, or you can just plot it using fooplot.com or wolframalpha.com and see what the x-value is when the y-value is 60.
Hope I helped!
Darry