Question 1114704
distance=rate*time; rate= speed of boat (b)+ speed of current (c) or 4+c down stream and 4-c upstream
48=(4+c)* time
16=(4-c)*time

time is the same
time=48/(4+c)
time=16/(4-c)
set the two equal.

48/(4+c)=16/(4-c)
cross-multiply
192-48c=64+16c
64c=128
c=2 feet per second  ANSWER
boat goes 6 ft/sec downstream and takes 8 seconds to go 48 feet
boat goes 2 ft/sec upstream and takes 8 seconds to go 16 feet