In a 100 m race, A beats B by 10 m and B beats C by 10 m. By what distance does A beat C (in m)?

19 18 20 21

19

According to the question, A = B + 10, B = C + 10, Therefore     A   :   B   :   C                   10  : 9                         : 10  :  9                  100  :  90 : 81 ⇒ The distance by which A beat C = 100 - 81 = 19m.