If Deepesh had walked 20 km/h faster he woulh have saved 1 hour in the distance of 60km. what is the usual speed of Deepesh?

Let the original speed  be x km/h, then

$\frac{600}{x}-\frac{600}{x+20}=1$ 

$\Rightarrow 600\frac{x+20-x}{xx+20}=1$  

$\Rightarrow x2+120x-12000=0$

$\Rightarrow x-120x-100=0$

Therefore,  original speed = 100km/h