<PRE><B>Question 729047</B>
D=RT
47=(15+C)T 
40=(20-C)T 
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87=35T
T=87/35
T=2.5 HOURS.
47=(15+C)2.5
47=37.5+2.5C
2.5C=47-37.5
2.5C=9.5
C=9.5/2.5
C=3.8 MPH. IS THE CURRENT SPEED.
PROOF:
40=(20-3.8)2.5
40=16.2*2.5
40=40</PRE>