Problem 8
Answer: Approximately 17.45 miles per gallon
-----------------------
Step-by-step explanation:
You divide the number of miles over the number of gallons to get this result
384/22 = 17.45
Another way you could think of it is to say
384 miles = 22 gallons
Then you divide both sides by 22 getting
17.45 miles = 1 gallon
Showing that 1 gallon of gas gets you roughly 17.45 miles
=============================================
Problem 9
Answer: Approximately 46.933 feet per second
---------------------
Step-by-step explanation:
Check out the attached diagram below. For the first column, I placed "32 miles" over "1 hour" to indicate "32 miles per hour". The second column is from the idea that 1 hour = 60 minutes. This helps us convert from hours to minutes. Note how the "hour" units cancel when we divide.
The third column helps us convert from minutes to seconds. We have the "minutes" units cancel out when they divide. It's important that one "minute" unit is on top, and the other is on the bottom. Finally, the last column helps us convert from miles to feet since 1 mile = 5280 feet.
Once this table formed, you multiply the numbers across the top to get 32*1*1*5280 = 168960
And you multiply everything along the bottom row: 1*60*60*1 = 3600
The last step is to divide the two results (top row over bottom row) getting
168960/3600 = 46.933 approximately
So 32 mph converts to roughly 46.933 ft per second.
Side note: the conversion method I used is called the "railroad method" or "railroad tracks method" as the table lines form what appears to be railroad tracks of sorts.