Rakesh is standing at a point. He walks $20 \; \text{m}$ towards the East and further $10 \; \text{m}$ towards the South, then he walks $35 \; \text{m}$ towards the West and further $5 \; \text{m}$ towards the North, then he walks $15 \; \text{m}$ towards the East. What is the straight distance in metres between his starting point and the point where he reached last $?$
- $0$
- $5$
- $10$
- $15$