After 7 hours of driving, who is farther from his or her home? by how much?

Sally is increasing her distance by 15 miles an hour while Ben is increasing his by 50 miles per hour.
Sally is 100 miles away at 5 hours so add 15 x 2 to 100 gives you 130 miles. This is how far away she is at 7 hours.
Ben is 250 miles away at 5 hours so add 50 x 2 gives you 350 miles. this is how far away he is at 7 hours.
350-130=220, Ben is the furtherst away by 220 miles.