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.
11 + 5 x 4a
Hope this helps! Do you need an explanation?
Answer:
last option from the left
Step-by-step explanation:
To find the price of one water bottle, we can calculate 6 / 24 because 24 bottles cost $6. Now, to find the price of 10 bottles, we can multiply the price of 1 bottle by 10 so the answer is 6 / 24 * 10.