question: A local gas station is selling gas for $3.00 a gallon.  An app company is offering $.20 cashback per gallon if you fill up at this station.  If someone buys 10 gallons of gas, how much with their gas be, after the cashback rewards?
answer: Gas is $3.00 a gallon and they buy 10 gallons of gas so that's 3*10 = $<<3*10=30.00>>30.00
  The app is offering $0.20 cashback per gallon and they buy 10 gallons so that's .20*10 = $<<0.20*10=2.00>>2.00
  They spent $30.00 on gas and their app is offering them $2.00 cashback so they spent 30-2 = $<<30-2=28.00>>28.00 per gallon
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