<PRE><B>Question 840608</B>
70 minutes against wind or {{{7/6}}} hours;
r plane if no wind
w speed of wind


{{{R*t=d}}}, for Rate, Time, Distance


_________________speed___________time___________distance
AGAINST__________r-w_____________7/6____________d={{{(r-w)(7/6)=175}}}
WITH_____________r+w_____________5/6____________d={{{(r+w)(5/6)=175}}}


Two equations in the two unknowns, r and w.  Both equations linear.</PRE>