I travelled from London to Glasgow last week at 60 miles per hour, I had filled my petrol tank just before I left, so it was full with 25 gallons.
Unfortunately, my petrol tank sprang a leak immediately and I only managed to drive 300 miles before I ran out of petrol.
My car does 30 miles per gallon, how fast was I losing petrol through the hole?
Answer: 3 gallons per hour.
I drove 300 miles at 30 miles per gallon, so I used 10 gallons. Which means I lost the other 15 gallons.
I drove the 300 miles at 60mph, which took me 5 hours.
So I lost 15 gallons of petrol in 5 hours = 3 gallons per hour.