A person travelled a distance of 200km between two cities by a car covering the first half distance of the journey at a constant speed of 40km/h and remaining half at a constant speed of v km/h . If the average speed of the person for the entire journey is 48km/hr, find v

time taken for first half of the journey-100/40=10/4 hr
time taken for the second half of the journey=100/v hr
total time taken=10/4 +100/v=10v+400/4v
​average speed=total distance/total time    
-->48=200*4v/10v+400
-->200*4v=480v+19200
-->800v-480v=19200
-->320v=19200
v=60 km/hr