at 2:30, they are 70 miles away, at 2:45, they are 55 miles away.
That means, in 15 minutes, they traveled 15 miles....thats 1 mile per minute.
so 2:45....55 miles away...at 1 mile per minute = 2:45 + 55 minutes =
3:40. <== when they arrive at Grandma's house.
3:40 - 1:00 = 2:40.....it took 2 hrs and 40 minutes for the trip....thats 120 + 40 = 160 minutes <== =so the family lives 160 miles from Grandma's house
