A rower can row 7 km/h in still water. When the river is running at 1 km/h, it takes the rower 1 hour to row to Big Rock and back. How many kilometers is it to Big Rock?  Select
A) 3.19	B) 3.28	C) 3.35	D) 3.43	E) 3.56

Rationale: "let x be the distance to big rock . time = x / 6 + x / 8 = 1 x = 48 / 14 = 3.43 km the answer is d ."
Answer: D