Question: a man swims downstream 30 km and upstream 18 km taking 6 hours each time , what is the speed of the man in still water ?
A) 7
B) 8
C) 5
D) 2
E) 4
Correct answer: E
Grade: 6 | Topic: Ratios and proportions | Difficulty: Hard | Standard: 6.RP.A.3b