Physics

I believe we can use similar triangles to solve this

In one second the current rate is 29/36m/s   and the swimmer's rate is 20/36m/s...so...

29/20  = d/500   where d is the distance downstream ....multiply both sides by 500

500*29/20 = d =  725m

Another method:

How long did it take him to swim across the river 500m

500m/2000km/hr= 1/4 hr = 15 mins

So for 15 mins he was being taken downstream at 2.9km/hr

2.9 km/hr x 1/4 hr = .725km = 725 meters downstream

~jc

It is good to see you ~jc,  The children have been pining over your absense. :)