Well, first, find-out how fast he was going the first time, by dividing 310 by 5. This gives you 62 mph. Now, divide 403 miles by 62 miles per hour in order to find-out how long it would take him to drive 403 miles, if he is constantly doing 62 mph. Your final answer is six-and-a-half hours.
a = 46c....for c
a/46 = c
322 = 46c
322/46 = c
7 = c.....7 circuits are required
-5 is your y-intercept so you would start at point(0,-5)
then you go up seven and to the right 1
the graph is attatched