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You can put this solution on YOUR website!
Going to parent's house in 4.5 hours. Travel by car (60 mph) to dock where I'll enter a boat (20 mph on still water with 4 mph current...against me on the way to parent's house...with me on the way back). Takes 3.5 hours to get back home. What's the distance?
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\n" ); document.write( "This easiest way, is to find the time he was on the road at 60 mph and go on from there.
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\n" ); document.write( "Let t = his time at 60 mph
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\n" ); document.write( "Then (4.5 - t) = boat time at 16 mph
\n" ); document.write( "And (3.5 - t) = boat time at 24 mph
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\n" ); document.write( "We know the trip there and the trip back are equal in distance; dist = speed*time:
\n" ); document.write( "60t + 16(4.5-t) = 60t + 24(3.5-t)
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\n" ); document.write( "Subtract 60t from both sides, and multiply what's inside the brackets:
\n" ); document.write( "72 - 16t = 84 - 24t
\n" ); document.write( "-16t + 24t = 84 - 72
\n" ); document.write( "8t = 12
\n" ); document.write( "t = 12/8
\n" ); document.write( "t = 1.5 hrs at 60 mph
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\n" ); document.write( "Total distance would be:
\n" ); document.write( "1.5(60) + 16(4.5-1.5) =
\n" ); document.write( "90 + 16(3) =
\n" ); document.write( "90 + 48 = 138 miles
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\n" ); document.write( "Check solution using return trip:
\n" ); document.write( "1.5(60 + 24(3.5-1.5) =
\n" ); document.write( "90 + 24(2) =
\n" ); document.write( "90 + 48 = 138 mi also
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\n" ); document.write( "Did this make sense to you?\r
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