Answer:
x = 61 mph
the average speed on the level Road is 61 mph
Explanation:
Let x represent Best's average speed on the level road. (In mph)
Best's average speed on the winding road = x-20
Given;
Total distance travelled = 571 miles
Time travelled on level road = 6 hours
Time travelled on winding road = 5 hours
Distance travelled = average speed × time taken
Total distance travelled can be written as
6 × (x) + 5×(x-20) = 571
6x+5x-100 = 571
11x = 571+100
11x = 671
x = 671/11
x = 61 mph
the average speed on the level Road is 61 mph