document.write( "Question 1075485: A tourist traveled on a motorboat against the current for 25 km. And then returned back on a raft. In the boat the tourist traveled for 10 hours less than on the raft. Find the speed of the current if the speed of the motorboat in still water is 12 km/hour. Show your work! \n" ); document.write( "

Algebra.Com's Answer #690140 by jorel1380(3719) $\"\"$ $\"About$

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Let n be the amount of time it takes to travel the river, and c be the speed of the current. Then:
\n" ); document.write( "25/(12-c)=25/c -10
\n" ); document.write( "25c=25(12-c)-10(c)(12-c)
\n" ); document.write( "25c=300-25c-120c+10c²
\n" ); document.write( "10c²-170c+300=0
\n" ); document.write( "c²-17c+30=0
\n" ); document.write( "(c-15)(c-2)=0
\n" ); document.write( "c=15 or 2
\n" ); document.write( "Since a value of 15 would give a negative result for the motorboat trip, we get a logical value of 2 kph as the speed of the current. ☺☺☺☺ \n" ); document.write( "

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