Question 958185
At 21 mph for 1/2 an hour, Lou has a 10.5 mile head start, so he has 35mi-10.5mi=24.5 miles to go to the first stop. 24.5mi/21mph=1.167hr
Lou will be at the stop in 1.167 hrs, so his friends must drive 35 miles in 1.167 hrs or 35mi/1.167=29.99 miles per hour ANSWER: They must drive 30 miles per hour.