document.write( "Question 593008: 2. A train required 2 h longer to travel 500 km than a plane required to travel 1200 km. Find the speed of the train, if the plane travels 4 times as fast as the train. \n" ); document.write( "

Algebra.Com's Answer #376148 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+s+\"$ = the speed of the train
\n" ); document.write( " $\"+4s+\"$ = the speed of the plane
\n" ); document.write( "Let $\"+t+\"$ = time for the plane
\n" ); document.write( " $\"+t+%2B+2+\"$ = time for the train
\n" ); document.write( "---------
\n" ); document.write( "Equation for the train:
\n" ); document.write( "(1) $\"+500+=+s%2A%28+t+%2B+2+%29+\"$
\n" ); document.write( "Equation for the plane:
\n" ); document.write( "(2) $\"+1200+=+4s%2At+\"$
\n" ); document.write( "---------------
\n" ); document.write( "This is 2 equations and 2 unknowns,
\n" ); document.write( "so it's solvable
\n" ); document.write( "(1) $\"+500+=+s%2At+%2B+2s+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+s%2At+=+1200%2F4+\"$
\n" ); document.write( "(2) $\"+s%2At+=+300+\"$
\n" ); document.write( "Substitute (2) into (1)
\n" ); document.write( "(1) $\"+500+=+300+%2B+2s+\"$
\n" ); document.write( "(1) $\"+2s+=+200+\"$
\n" ); document.write( "(1) $\"+s+=+100+\"$
\n" ); document.write( "The speed of the train is 100 km/hr
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+1200+=+4s%2At+\"$
\n" ); document.write( "(2) $\"+1200+=+4%2A100%2At+\"$
\n" ); document.write( "(2) $\"+t+=+3+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+500+=+s%2A%28+t+%2B+2+%29+\"$
\n" ); document.write( "(1) $\"+500+=+100%2A%28+3+%2B+2+%29+\"$
\n" ); document.write( "(1) $\"+500+=+100%2A5+\"$
\n" ); document.write( "(1) $\"+500+=+500+\"$
\n" ); document.write( "OK \n" ); document.write( "

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