After you delivered your cakes to your grandma, you took her car to your brother's house. When you started the journey to return it, you put ten gallons of fuel in it. As the car is very old, you are forced to go at a steady 30 miles per hour, and each gallon gives you 20 miles. The tank also lost half a gallon of fuel every hour from leakage. After you left from your brother's house, you had enough fuel to barely make it. How far away is your grandma's house from your brother's?