Anglais et maths : calcul de distance et directions

You are standing at the Tourist Information Center. You need to reach the City Library. Follow the directions carefully: 1. Go straight ahead on Baker Street for $200$ meters. 2. Turn left at the second intersection onto Oxford Road. 3. Walk past the Park and the Post Office. 4. The Library is located $50$ meters after the Post Office, on your right side. If the total distance covered is $D$, calculate the distance of the final segment relative to the total path, given that the segment on Baker Street is $x = 200$ meters and the segment on Oxford Road is $y = 350$ meters. Calculate the ratio $R = \frac{50}{D}$ where $D = x + y$.