First, lets find how many miles the cyclist can ride per minute (speed = distance/time).
18/45 = 0.4 miles per minutes
Second, lets find how many miles the cyclist can ride per hour.
0.4 * 60 = 24 miles per hour
Third, lets find how many miles teh cyclist can ride in 6 hours.
24 * 6 = 144 miles in 6 hours
Best of Luck!
