posted by mark .
john's columm covered the first 12 miles in 4 hours. he then increased the speed by 2 miles per hour. if the total distance of the trip was 52 miles, how long did it take to finish the trip
speed of first part = 12miles/4hrs = 3 mph
speed of 2nd part = 5 mph
distance left to cover = 40 miles
time = 40 miles/(5 mph) = 8 hrs.