What are the answer options?
We have been given that the upstream speed is
and the down stream speed is
.
Let the fisherman traveled a distance of x miles.
The total time of the trip is 6 hours.
Relations between speed (s), time (t) and distance (d) is 
Hence, 
Time upstream + time downstream = 6

lcm = 10

=> 
Cross multiplying, 
x = 20 miles .. Answer.
(-4 1/2) / (-2 2/3) =.....turn to improper fractions
(- 9/2) / (-8/3) =...when dividing fractions, flip what u r dividing by, then multiply
-9/2 * -3/8 =
27/16 =
1 11/16 <==