Question

After visiting my Great Aunt Annie, I travelled home in her old jalopy. The
car was old and battered, it had a leak from the petrol tank, and I was stuck in second gear. This meant that I could only travel along at a steady 30 miles per hour and managed a paltry 20 miles per gallon of fuel. At the start of the journey i had placed exactly 10 gallons of fuel
into the tank. I knew though, that the fuel tank lost fuel at the rate of half
a gallon per hour. Just as I arrived home, the car stopped because run out of fuel and I had only just made it. How far it was from my Aunt's to my home?
​

Answer 1

150 miles. I was travelling at 30mph at a rate of 20mpg, so I was using 1.5 gallons every hour for the driving itself. I was also losing 0.5 gallon every hour, so in total, I was using 2 gallons every hour. Therefore to use all of the 10 gallons I started with, I travelled for 5 hours. 5 hours at 30mph is 150 miles.