Question 305389

Just looking at the units and no numbers:
(miles driven) / (mi/gal) = gallons consumed
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{{{20000/21.6 = 925.926}}} gallons consumed in a year
{{{20000/20.8 = 961.538}}} gallons consumed in a year
{{{961.538 - 925.926 = 35.612}}}
She saves 36 gallons in a year by increasing tire pressure