Question 606971
Andy's average driving speed for a 4-hour trip was 45 miles per hour.
 During the first 3 hours he drove 40 miles per hour.
 what was his average speed for the last hour of his trip?
:
let s = speed on the last hr
;
Write a distance equation; dist = speed * time
40(3) + 1s = 45(4)
120 + s = 180
s = 180-120
s = 60 mph on the last hr