math
posted by john .
The speed of a stream is 6 mph. If a boat travels 52 miles downstream in the same time that it takes to travel 26 miles upstream, what is the speed of the boat in still water?

let the speed of the boat in still water be x mph
using Distance = rate x time or Time = distance/rate
upstream:
time = 26/(x6)
downstream:
time = 52/(x+6)
26/(x6) = 52/(x+6)
crossmultiply
52x  312 = 26x + 156
26x = 468
x = 18
boat's speed is 18 mph