Question 5
Phuong Vy walks from her home $V$ to her grandmother's home $B$ along a route with level, uphill and downhill sections. Her speeds are 5 km/h on level ground, 4 km/h uphill and 6 km/h downhill. The outward journey takes 1 hour 36 minutes; the return along the same route takes 1 hour 39 minutes. The level sections total 2.5 km. Find the length of the route from $V$ to $B$.
