Question 133375
Given: Still speed of 760km/hour. Can travel 2000km with the wind in the same time as it can go 1800km against the wind.

Let w = windspeed.

{{{distance = velocity * time}}}
{{{2000 = (760+w) * t }}}
{{{ ((2000)/ (760+w) ) = t }}}  with the wind

{{{distance = velocity * time}}}
{{{ 1800 = (760-w) * t }}}
{{{ (1800/ (760-w)) = t}}} against the wing

t is the same in both cases, so
{{{(2000)/(760 +w) = (1800)/(760-w)}}}
{{{ (2000)(760-w) = (1800)(760+w) }}}
{{{ (200)(760) = 3800 w }}}
{{{w = 40 }}}

Check your answer. 2000/(760+40) = 2.5
1800/(760 -40) = 2.5 Check!