Answer:
The y-intercept is 210 miles. (Each vertical division is 30 miles.)
The y-intercept is the number of miles to go when Juniper hasn't started driving, so is the initial distance to exit 34. (correct)
The slope is the rate of change of distance to the exit. (correct)
The slope of the graph is -60 mph, not 60 mph. A graph that goes down to the right has negative slope.
The y-value is miles remaining. There is nothing on this graph that shows miles driven.