Answer:
Looking at graphs we count the distance at the side for every change point, imagine a distance going 10miles and then staying at 10 miles on the second hour we keep 10 miles and pick the next new number as the linear graph moves up.
We do not count any horizontal lines twice as this shows stationary journeys meaning constant time, we know time is always at the bottom of graphs and just count the points by matching each point to the distance until you get from 0-7 hrs across the graph.
We show the numbers also as they descend as this counts as positive hours too. A descent in miles is not a descend in hours so the mileage gets bigger if we are reading it left to right and slopes descend.
Step-by-step explanation:
y = 350 miles
count to see if they are more than 350miles on the line as it goes up across and down, counting only once if it stays straight, and count again if its straight at any other point. always count from a to b to c etc.
y = 455 miles
count to see if they are more than 455miles on the line as it goes up across and down, counting only once if it stays straight, and count again if its straight at any other point. always count from a to b to c etc.
y = 140 miles
count to see if they are more than 140miles on the line as it goes up across and down, counting only once if it stays straight, and count again if its straight at any other point. always count from a to b to c etc.
y = 280 miles
count to see if they are more than 280 miles on the line as it goes up across and down, counting only once if it stays straight, and count again if its straight at any other point. always count from a to b to c etc.
, so you have
is measured in radians, so 
.