At a local gas station, regular gasoline sells for $2.899 per gallon, while premium gasoline sells for $3.379 per gallon. How much does a person save on 15.25 gallons of gas by buying regular instead of premium?

1 Answer
Tony B
Mar 13, 2017

#$7.32 #

Explanation:

Difference in unit price (cost for 1 gallon)

#$3.379#
#ul($2.899) larr" subtract"#
#$0.48 " "larr" saving for each gallon bought"#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose you do not have a calculator. This is a trick that will work with these particular numbers

5 is #1/2# of 10

#10xx$0.48 ->$4.80#
#1/2xx$4.8color(white)(.)->ul($2.40) larr" add"#
#" "$7.20#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The 0.25 from #15.25# is the same as #1/2xx1/2#

#1/2xx$0.48 = $0.24#
#1/2xx$0.24=$0.12#

So putting it all together we have:

#10xx$0.48 ->$4.80#
#1/2xx$4.8color(white)(.)->ul($2.40) larr" add"#
#" "$7.20#
#" "ul($0.12) larr" add"#
#" "$7.32#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Check by calculator: #15.25xx$0.48=$7.32 #

Related questions
Impact of this question
3027 views around the world
You can reuse this answer
Creative Commons License