Answer :
Explanation :

1. How to find Speed(s) if distance(d) & time(t) is given:    Speed (S) = Distance (D)Time (T)     Ex: Find speed if a person travels 4 kms in 2 hrs? Speed = D/T = 4/2 = 2 kmph.   2.  Similarly, we can find distance (d)  if speed (s) & time (t) is given by   Distance (D) = Speed (S) x Time (T)   Ex : Find distance if a person with a speed of 2 kmph in 2 hrs? Distance D = S X T = 2 x 2 = 4 kms.    3.  Similarly, we can find time (t) if speed (s) &  distance (d) is given by   Time (T) = Distance (D)Speed (S)   Ex : Find in what time a person travels 4 kms with a speed of 2 kmph? Time T = D/S = 4/2 = 2 hrs.   4. How to convert  km/hr into m/sec :   P km/hr = P x 518 m/sec   Ex : Convert 36 kmph into m/sec? 36 kmph = 36 x 5/18 = 10 m/sec    5. How to convert  m/sec into km/hr :   P m/sec = P x 185 kmph.   Ex : Convert 10 m/sec into km/hr? 10 m/sec = 10 x 18/5 = 36 kmph.   6.  If the ratio of the speeds of A and B is a:b, then the ratio of the times taken by them to cover the same distance is b : a.   7.  Suppose a man covers a certain distance at x km/ hr and an equal distance at y km/hr . Then, the average speed during the whole journey is 2xyx+y km/hr.