The destination is 420 mi away, and you're travelling at 70 mph. This means you travel 70 miles every hour. This leads to 420÷70, which is 6. The answer is 6 hours.
If you are traveling and each hour you cover 70 miles, and your destination is 420 miles away, divide the distance with your velocity. You just need to divide 420 miles into 70 (the velocity at which you're traveling) and you'll get 6 hrs.
