document.write( "Question 318787: A pontoon boat moves 6 km/h in still water. It travels 30 km upriver and 30 km downriver in total time of 18 hrs. What is the speed of the current? \n" ); document.write( "

Algebra.Com's Answer #228198 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
Rate*Time=Distance
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( "1. $\"%286-C%29%2AT1=30\"$ <--- Against the current
\n" ); document.write( "2. $\"%286%2BC%29%2AT2=30\"$ <--- With the current
\n" ); document.write( "3. $\"T1%2BT2=18\"$ <--- Total time
\n" ); document.write( "From eq. 1,
\n" ); document.write( " $\"T1=30%2F%286-C%29\"$
\n" ); document.write( "From eq. 2,
\n" ); document.write( " $\"T2=30%2F%286%2BC%29\"$
\n" ); document.write( "Then substitute into eq. 3,
\n" ); document.write( " $\"30%2F%286-C%29%2B30%2F%286%2BC%29=18\"$
\n" ); document.write( " $\"30%286%2BC%29%2B30%286-C%29=18%286-C%29%286%2BC%29\"$
\n" ); document.write( " $\"180%2B30C%2B180-30C=18%2836-C%5E2%29\"$
\n" ); document.write( " $\"360=648-18C%5E2\"$
\n" ); document.write( " $\"18C%5E2=288\"$
\n" ); document.write( " $\"C%5E2=16\"$
\n" ); document.write( " $\"highlight%28C=4%29\"$ km/h \n" ); document.write( "

\n" );