5 3/4 -4 1/10
= 23/4 -41/10
= 115/20 -82/20
= 33/20
= (20+13)/20
= 20/20+ 13/20
= 1+ 13/20
= 1 13/20
The final answer is 1 13/20~
We calculate both velocities:
upstream 8 miles in 2 hours = 4 miles / hour
downstream 8 miles in 1 hour = 8 miles / hour
ps -stream speed = 4 mph
ps + stream speed = 8 mph
Adding both equations
2 ps = 12 mph
paddling speed = 6 mph
stream speed = 2 mph
The number was 160 because 5/4•128=160. 5/4 represents inverting 80% and multiplying it by the number to determine how the result became 128. For checking over all you have to do is do 4/5 or 80%•160 which shall give you 128.