<PRE><B>Question 260910</B>
Speed against wind is 160 - v
Speed with wind is 160 + v
Time to fly 500 miles with wind is 500/(160 1+ v)
Time to fly 420 mile against wind is 420/(160 - v)
And they are equal
so 500/(160 + v) = 420/(160 - v)
multiplying up
500x(160 - v) = 420x(160 + v)
80,000 - 500v = 67200 + 420v
12800 = 920v
v = 12800/920 = 13.913 mph</PRE>