Answer:
Time taken to drive to her grandparents house = 6 5/6 hours We convert this mixed into improper fraction, we get = 41/6 hoursTime taken to drive to her grandparents house = 41/6 hoursTime taken to drive back = 8 2/9 hoursWe convert this mixed into improper fraction, we get = 74/9 hoursTime taken to drive back = 74/9 hoursDifference between the two = 74/9 - 41/6 = (148-123)/18 = 25/18 hours = 1 7/18 hoursTherefore it took 1 7/18 hours longer to drive back.