I drove to the beach at a rate of 40 miles per hour. If I had driven at a rate of 50 miles per hour instead, then I would have arrived 45 minutes later. How many miles did I drive?
From this, we can infer that going 10 mph faster will get you there 45 minutes earlier. This means x/50=x/40+0.75. When you solve for x, you get 150. You drove 150 miles!