SOLUTION: An aeroplane flies from A to B at a speed of 750km/h. On the return trip there was a strong tail wind and the airplane flew at 900km/h. The return flight took 20 min less than the

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Question 1029020: An aeroplane flies from A to B at a speed of 750km/h. On the return trip there was a strong tail wind and the airplane flew at 900km/h. The return flight took 20 min less than the original. How many hours did the return trip take?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = the time in hrs going from A to B
+t+-+1%2F3+ = the time in hrs on return trip
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Equation for A to B
(1) +d+=+750t+
Equation for B to A
(2) +d+=+900%2A%28+t+-+1%2F3+%29+
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By substitution:
(2) +750t+=+900%2A%28+t+-+1%2F3+%29+
(2) +750t+=+900t+-+300+
(2) +150t+=+300+
(2) +t+=+2+
and
+t+-+1%2F3+=+2+-+1%2F3+
+t+-+1%2F3+=+1+%2B+2%2F3+
and
+%282%2F3%29%2A60+=+40+ min
The return time is 1 hr and 40 min
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check:
(1) +d+=+750t+
(1) +d+=+750%2A2+
(1) +d+=+1500+ km
and
(2) +d+=+900%2A%28+2+-+1%2F3+%29+
(2) +d+=+900%2A%285%2F3%29+
(2) +d+=+1500+ km
OK