<PRE><B>Question 910337</B>
Use rate(r) * time(t) = distance (d)
we are given t1 = 3.2 hours against the wind,
t2 = 3 hours with the wind and rw of the wind is 7 mph
the distance traveled d is the same for against the wind and with the wind
so we can set our equations = to each other
let r be the speed of the plane, then
(r-7) * 3.2 = (r+7) * 3
3.2r - 22.4 = 3r + 21
subtract 3r from both sides of =
.2r -22.4 = 21
add 22.4 to both sides of =
.2r = 43.4
r = 217 mph
the speed of the plane is 217 mph
check the answer in our equation
(217-7) * 3.2 = (217+7) * 3
672 = 672
our answer checks out ok</PRE>