A Pumper takes nine minutes to reach the scene of a fire loc

A Pumper takes nine minutes to reach the scene of a fire located eighteen city blocks away. If one mile equals three city blocks, how fast is the truck traveling.

Solution

Set up all the conversions first, then use the
appropriate formula
1 mile = 3 blocks
1 block = 1/3 mile
18 blocks = 18/3 mile
18 blocks = 6 miles
9 minutes = x hours * 60 minutes/hour
x hours = 9 minutes / 60 minutes/hour
x hours = 3/20 hours
speed = distance / time
speed = 6 miles / 3/20 hour
speed =(6 * 20) / 3 miles / hour
speed = 120/3 miles /hour
speed = 40 miles/hour