Racer A runs 15 miles an hour, and she needs to travel 5 miles to get to racer B and hand off her racing baton. Racer B will then run 5 miles an hour faster than racer A, and travel 4 times as far. That’s the whole race. We want to know how long the whole race will take, and we know it takes racer A 20 minutes. How fast is racer B going, and what does the equation to find out how long she took look like?