Answer:  The usual time of Rakesh is 25 minutes.

Step-by-step explanation: Given that Rakesh runs at five-fourth of his usual speed and reaches the playground 5 minutes earlier.

We are to find the usual time of Rakesh.

Let s and t represents the original speed and the original time taken by Rakesh.

Then, we have

When the speed is five-fourth of the original speed t, then the time will be (t - 5).

So, we have

Thus, the usual time of Rakesh is 25 minutes.