Ethanol (C2H5OH) and gasoline (assumed to be all octane, C8H18) are both used as automobil...

Ethanol (C₂H₅OH) and gasoline (assumed to be all octane, C₈H₁₈) are both used as automobile fuel. If gasoline is selling for $2.79/gal, what would the price of ethanol have to be in order to provide the same amount of heat per dollar? The density and  of octane are 0.7025 g/mL and –249.9 kJ/mol, respectively, and of ethanol are 0.7894 g/mL and –277.0 kJ/mol. respectively (I gal = 3.785 L).