Question

 A boat goes 12 km upstream and 40 km downstream in 8 hours. It can go 16 km upstream and 32 km downstream is the same time. Find the speed of the boat in still water and the speed of the stream.

Answer 1

if the bot has speed b, and the stream has speed s, then since time=distance/speed,

12/(b-s) + 40/(b+s) = 8
16/(b-s) + 32/(b+s) = 8
b=6
s=2

check:
12/4 + 40/8 = 3+5 = 8
16/4 + 32/8 = 4+4 = 8