SBI PO 09 Jun 2019 Papers

A boat takes 3 hours more to travel upstream from X to Y than the time it takes to travel downstream from Y to Z. The speed of the boat downstream is 27 km/h and that upstream is 21 km/h. If the distance between X and Y is 51 km more than that between Y and Z, what is the distance between X and Y ? (in km)