Question 776680
Solve the problem in general.

r = speed in no wind
c = speed of the wind
r+c = speed of plane with the wind
r-c = speed of plane against the wind
u = distance traveled using r+c speed
b = distance traveled using r-c speed
h = a give amount of time for the situation ---- UNKNOWN in this situation


Equations are these:
{{{(r-c)h=b}}}
and
{{{(r+c)h=u}}}


You were given values for everything but not for c.  The question asks, find c, the speed of the wind.


The analysis is described and now, the rest of the solution process:
Against the wind, {{{h=b/(r-c)}}}.
With the wind, {{{h=u/(r+c)}}}
These expressions for h are equal.  They are equal, according to what was given.
'
{{{b/(r-c)=u/(r+c)}}}
{{{(r+c)b=u(r-c)}}}
{{{rb+bc=ru-uc}}}
{{{rb+bc+uc=ru}}}
{{{bc+uc=ru-rb}}}
{{{c(b+u)=r(u-b)}}}
{{{highlight(c=r(u-b)/(b+u))}}} and then substitute the given values.