Let x = velocity of dog
y = velocity of hare
t1 = time taken by dog to take one leap
t2 = time taken by hare to take one leap.
A dog takes 4 leaps for every 5 leaps
So,
4t1 = 5t2
=>t1/t2 = 5/4 ....(1)
3 leaps of the dog are equal to 4 leaps of the hare.
So, equating the distance covered
3*x*t1 = 4*y*t2
=>x/y = 4/3*t2/t1
=>x/y = 4/3*4/5 (From 1)
=>x/y = 16/15