Let's assume David's average speed is S km/h.
A) To find David's average speed, we can use the formula: Speed = Distance / Time.
David completed the race in 5 hours, so his speed is S km/h. Therefore, we have:
S = Distance / 5
B) Ken's average speed is 9.8 km/h less than David's average speed, which means Ken's average speed is (S - 9.8) km/h.
Ken took 7 hours to complete the race, so we have:
S - 9.8 = Distance / 7
Now, we can solve the system of equations to find the values of S and Distance.
From equation (1): S = Distance / 5
Substitute this into equation (2):
Distance / 5 - 9.8 = Distance / 7
Multiply both sides of the equation by 35 to eliminate the denominators:
7 * Distance - 35 * 9.8 = 5 * Distance
7 * Distance - 343 = 5 * Distance
Subtract 5 * Distance from both sides:
2 * Distance - 343 = 0
Add 343 to both sides:
2 * Distance = 343
Divide both sides by 2:
Distance = 343 / 2 = 171.5 km
Therefore, the distance of the cycling race is 171.5 kilometers.
To find David's average speed, substitute the distance into equation (1):
S = Distance / 5 = 171.5 / 5 = 34.3 km/h
So, David's average speed was 34.3 km/h.
