Christopher's best time in a race is four seconds faster than his second-best time. His second-best time is 1 1/3 times slower than his best time. Find his second-best time.
Second Best = Best + 4 sec (1)
(4/3)Best = Second Best (2)
Sub (1) into (2)
(4/3)Best = Best + 4
(1/3)Best = 4
Best = 12 seconds
Second Best = (4/3)Best = (4/3)12 = 48/3 = 16 seconds