(b) Let the time taken by Sanjit to walk to school = x min Similarly, the time taken by Sanjit to ride bicycle to school = y min Case I When Sanjit walks one way and rides the other ways x + y = 90 .... (i) Case II When Sanjit rides both way y + y =30 ... (ii) 2y = 30 y = 15 Now, x + y = 90 x + 15 = 90 ⇒ x = 75 ∴ Time taken by Sanjit to walk both ways = 75 + 75 = 150 min = 2.5 h