Question 1012151
c=current
trip downstream is 15 miles at (16+c) mph=15/(16+c) hr
trip upstream is 15 miles at (16-c) mph=15/(16-c) hr
Those two equal 5.5
It is D.
Multiply everything by (16+c)(16-c)
240-15c+240+15c=1408-5.5c^2
5.5c^2-928=0
The current is about 13 km/h
downstream at 29 km/h (about) takes just under a half hour.
upstream at 3 km/h takes about 5 hours.