Piyush and Kesari start at the same time to travel from place P to Q, which is 100 kms apart .  Piyush travels 5 km/h slower than Kesari . Kesari reaches place Q and at once turns back meeting Piyush, 20 kms from place Q .  Kesari's speed (in km/h) is ?

15

Let speed of Piyush = S

     Speed of Kesari = S + 5

Distance travelled by Kesari = (100 + 20) = 120

Distance travelled by Piyush = (100 - 20)  = 80

As per question, 

 \(\frac{120}{S + 5}\) = \(\frac{80}{S}\)

  120 S = 80 S + 80 × 5

    40 S = 80 × 5

        S = 10 km/h

Speed of Kesari = S + 5 = 10 + 5 = 15 km/hr