Yes it is proportional because the vehicle is moving at a constant speed of 41 mph (as 92/2=41). So if you don't drive, your speed is 0 mph which is accurate in regards to the graph.
Problem 10:
No it is not because due to the y-intercept not being 0, y doesn't vary directly with x. However, the slope remains constant, but it's not the same thing as proportional
