<PRE><B>Question 985726</B>
One tank of gas will take a car 400 km if the car is driving at 100 km/hr.
 However if the car is driven at 50 km/hr the rate of gas consumption is 1/3 less.
 How much longer (in km) will a car be able to drive on one tank of gas, at 50 km/hr rather than at 100 km/hr?
:
This would be easier to handle if we gave the gas tank a value of 20 gallons
Then the mpg would be: 400/20 = 20 kpg
In terms of consumption the is 1/20 or .05 gal per km 
A consumption of 1/3 less would be 2/3 * .05 = .0333 gal per km
Find how many miles to empty the tank at this consumption, 20/.0333 = 600 km
therefore
600 - 400 = 200 km further at 50 km/hr

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