Namit starts from a point 'Z' and travels 4 km towards west to reach 'Y'. Then he takes a left turn and covers 2.5 times the distance covered between 'Y' and 'Z' and reaches at point 'X'. From there he takes a left turn and travels 4 km to reach destination 'B'. Then he takes a left turn and covers some distance and walks 2 km ahead of Z to reach point 'A'. What is the shortest distance between 'A' and 'B' and the direction of B with respect to A?