Answer:
The average speed on level road is 65 mph
Step-by-step explanation:
Let the speed on the winding road be x mph
So the speed on the straight road will be x +20 mph
Mathematically, distance = speed * time
Distance on level road will be;
(x + 20)2
Distance on winding road will be;
x* 4 = 4x
Thus, we have;
2(x + 20) + 4x = 310
2x + 40 + 4x = 310
6x + 40 = 310
6x = 310 - 40
6x = 270
x = 270/6
x = 45 mph
The average speed on the level road is x + 20
That will be 45 + 20 = 65 mph