speed.
In equation form, speed is:
v+=+d%2Ft
if the time when airplane travels with the wind is t1 and the time when airplane travels against the wind is t2, we are given that t1=t2...we will use t
so, if it travels 3699 miles with the wind and has a speed of 380+mph, we have
380+mph+=+3699m%2Ft ....now calculate the time t
380+mph+%2At=+3699m
+t=+3699m%2F380+mph
+t=+3699cross%28m%29%2F380cross%28m%2Fh%29
+t=+%283699%2F380%29h
+t=+9.7h.....now we know the time and we can plug it in formula for speed against wind where d=3141m using same time
v+=+3141m%2F9.7h
highlight%28v+=+323.8mph%29 .........your answer