Right, so the whole distance between the holiday destination and his home is going to be 4/4. If you take the 1/4 away from 4/4, you have 3/4. This means the distance between the petrol station and his home must be 3/4 of the way. The distance between the petrol station and his home is 500 + 100, which is 600. So 600 = 3/4 of his journey. To get 1/4 you just divide that by 3, so you get 200.
So the answer is D x
