Let the speeds of Prakash and Arpit be 2x and 5xrespectively. Let’s assume that Arpit turned back frompoint Q as shown in the figure given below, ran at aspeed of x after turning back and met Prakash atpoint R, ‘t’ hours after they started running
From the given conditions, 2x×t=10=5x×2−x×(t−2) => t = 4 So the running speed of Prakash =2x=