Need help on math

Question

Michael drove to a friends house at a rate of 40 mph. he came back the same route, but at a rate of 45 mph. if the round-trip took 4 hours, what is the distance Michael traveled to visit his friend?

Answer 1

Round Trip took 4 hours. Let X = number of hours at 40 mph Then 4-X is the number of hours at 45 mph since X and 4-X add up to 4. The distances are the same so RT = RT; 40X = 45 (4-X); Solve for X; 85X=180; X = 36/17 hours (2.1176 hours) going. The distance going = distance returning = 40X = 40 (36/17) = 1440/17 miles (84.706 miles) each way or 2880/17 miles round trip (169.4118).