gasoline is a kind of fuel & fuel is a kind of resource ->  gasoline is a kind of resource  gasoline is a kind of resource & as the use of a resource decreases , the length of time that resource being available will increases ->  as the use of gasoline decreases, the length of time that gasoline is available will increase  as the use of gasoline decreases, the length of time that gasoline is available will increase & as mileage per gallon of gasoline increases , the amount of gasoline used will decrease ->  as mileage per gallon of gasoline increases, the length of time that gasoline is available will increase  as mileage per gallon of gasoline increases, the length of time that gasoline is available will increase & oil is a source of gasoline ->  as mileage per gallon of oil increases, the amount of time that oil is available will increase  as mileage per gallon of oil increases, the amount of time that oil is available will increase & to increase something can mean to extend somthing -> as mileage per gallon of oil increases, the amount of time that oil is available will be extended