Let distance between school and house = d km and ideal time to reach school = t hours When he walks at a speed of 5 km/hr, he reaches school 3 minutes late, ⇒ using distance = speed × time ⇒ d=5×(t+
3
60
)---------------(i) Similarly,d=9×(t−
3
60
)--------------(ii) Comparing, equations (i) and (ii), we get : ⇒ 5(t+