Question 833318
_________________speed_____________time_______________distance
upstream_________r-c_______________x__________________d
downstream_______r+c_______________y__________________d
total______________________________h


The table uses only variables, but some of the values are these:
d=600 miles
h=9 hours
c=16 miles per hour, the jet stream speed


x and y are variables, BUT THEY CAN BE HANDLED ACCORDING to r*t=d, t=d/r, so applying this,


_________________speed_____________time_______________distance
upstream_________r-c_______________d/(r-c)__________________d
downstream_______r+c_______________d/(r+c)__________________d
total______________________________h


NOW we can make one equation in one unknown variable.
{{{highlight(highlight_green(d/(r-c)+d/(r+c)=h))}}}
Solve for r; this will be a formula for r all in symbolic form.
Substitute the given values; and then compute r.