Question 161390
D=RT
80=(D+4)T
40=(D-4)T
SEEING AS THE TIMES ARE THE SAME WE HAVE:
80/(D+4)=40/(D-4)
80(D-4)=40(D+4)
80D-320=40D+160
80D-40D=160+320
40D=480
D=480/40
D=12 MPH FOR THE CURRENT.
PROOF;
80/(12+4)=40/(12-4)
80/16=40/8
16*40=80*8
640=640
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Hi Thank you for your time.  One that I simply cannot get is:  An airplane 
travels 600 miles against the wind in 4 hrs. and makes the return trip with the 
same wind in 2 hrs.  Find the rate of the wind.  The answer is either: 75, 150, 
225, or 300mph.  I can't seem to get the formula and it is driving me crazy!  
Can you help?
D=R*T
600=R*4
R=600/4=150 MPH AGAINST THE WIND.
600=R*2
R=600/2=300 MPH WITH THE WIND.
(300-150)/2=150/2=75 MPH IS THE SPEED OF THE WIND.

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