Answer:
6 Hours
Explanation:
When Lafayette led the column, the troops marched 24 miles in 6 hours.
Distance = 24
Time = 6
Speed = Distance/Time = 4
Then he left and the troops reduced their speed by 1 mile per hour.
Speed = 3
How long did it take them to march the last 18 miles.
Speed = 3
Distance = 18
Time = Distance/Speed = 6
6 Hours