Three friends A,B and C started from P towards Q which is 5km away. They have one cycle and only one person rides a cycle at a time . A , B and C walk at speeds of 4 , 5 and 6 km/hr and can ride the cycle at 7 , 8 and 10 km/hr respectively . Find the minimum number of time in which all three of them will reach the destination ? { All three person will reach when the last person will reach the destination }