Gasoline varies in cost from $0.98 to $1.18 per gallon. If a car’s mileage varies from 16 to 24 miles per gallon, what is the difference between the most and least that the gasoline for a 480-mile trip will cost?  Choose the correct choice.
A) $15.10	B) $15.30	C) $15.50	D) $15.75	E) $15.80
Solution:   We know that the per gallon cost of gasoline varies from $0.98 - $1.18.   Now we want to find the MAXIMUM difference between the least amount of money spent on gasoline and the largest amount of money spent i.e. to calculate max. trip cost - min. trip cost.   Mileage is given to be 16 to 24 miles per gallon, thus to travel 480 miles you will need gasoline in the range 480/24 to 480/16 which is 20 to 30 gallons.   So, for these 20 gallons and 30 gallons of gasoline the cost is as follows: (divide this task into 2 parts, 1 for 30 gallons and 2nd one for 20 gallons).   Case 1: for 30 gallons the cost is 30*0.98 to 30*1.18 which is $29.40 to $35.40   Case 2: for 20 gallons the cost is 20*0.98 to 20*1.18 which is $19.60 to $23.60   Thus, the maximum cost of the 480 mile trip is $35.40 and minimum is $19.60   so the difference is $35.40 - $19.60 = $15.80   Answer: $15.80 35.40 -  19.60= 
<gadget id="calculator"> 35.40 -  19.60</gadget>
<output>15.8</output>
$15.80   Answer: $15.80
<result>E</result>
Gasoline varies in cost from $0.98 to $1.18 per gallon. If a car’s mileage varies from 16 to 24 miles per gallon, what is the difference between the most and least that the gasoline for a 480-mile trip will cost?