Question

a walks at uniform rate of 4km an hour 4 hours after his start b cycles after him at 10kmph how far wil b catch a after d starting poin

Answer 1

after 4 hours, A is 16 km away
B starts, and bikes for T hours. B goes 10*T km
meanwhile, A continues walking and will be 16 + 4*T
they meet when those distances are the same:
10T= 16+4T
solve for T to find how long it takes B to catch A
then use Distance = 10*T to find the distance from the starting point