An woman swims downstream 64 km and upstream 24 km taking 8 hours each time; what is the speed of the current?
Choose one.
A) 1.6  B) 1.8  C) 3.5  D) 1.5  E) 2.5

Rationale: "64 - - - 8 ds = 8 ? - - - - 1 24 - - - - 8 us = 3 ? - - - - 1 s = ? s = ( 8 - 3 ) / 2 = 2.5 answer : e"
Answer: E