NTSE Stage 2 MAT 2018 Exam Question Paper

In a city, all the roads are either parallel to the East-West or North-South direction. Every $\frac{1}{8}$ th of a kilometre from each road there is a crossing and the square area covered between four crossings is called a block. Staring from a crossing. if I travel four blocks north. take left and then travel three blocks west. I reach another crossing. What is the distance between these two crossings?