Error! Because that does not make any sense
The factor of mn+5m-3n-15 is 6m-4n-15.
14gallons=380miles
14/380=<span>0.03684210526gallons/mile
</span>
418*<span>0.03684210526=15.4gallons
</span>
or you could cross multiply
14gallons=380miles
x gallons=418miles

380x=5852
divide both sides by 380
x=15.4 gallons
.167 feet per hour
I hope this helps