A man can row 9 kmph in still water. When the river is running at 3.1 kmph, it takes him 1 hour to row to a place and black. What is the total distance traveled by the man?
Choose the correct choice from the following choices
A) 2.21 B) 2.48 C) 9.24 D) 7.29 E) 7.94

Rationale: "m = 9 s = 3.1 ds = 12.1 us = 5.9 x / 12.1 + x / 5.9 = 1 x = 3.97 d = 3.97 * 2 = 7.94 answer : e"
Answer: E