Answer:
John waited for Brain at the finish line for a half-hour. (or 30 minutes)
Explanation:
The rule of the distance is D = s × t, where
- s is the speed to travel the distance D
- t is the time taken to cover the distance D
Let us use this rule to solve the question
∵ John's speed = 10 miles/hour
∵ Brian's speed = 8 miles/hour
→ Slower speed takes more time
∵ The distance of the trip is 20 miles
∴ D = 20 miles
→ Find the time of each one, using the rule above
∵ D = s × t
→ Find John's time
∴ 20 = 10 × t
∴ 20 = 10t
→ Divide both sides by 10
∴ 2 = t
∴ John's time = 2 hours
→ Find Brian's time
∴ 20 = 8 × t
∴ 20 = 8t
→ Divide both sides by 8
∴ 2.5 = t
∴ Brain's time = 2.5 hours
→ Subtract their times to find for how long John waited
∵ 2.5 h - 2 h = 0.5 h
∴ The difference between their times is 0.5 hour
∴ John waited for Brain at the finish line for a half-hour (or 30 minutes)