document.write( "Question 1153876: Over a distance of 120 km , the average speed of a train 40 kmh faster than the speed of a car the train covers the distance in 30 minutes las me , in the speed of The train? \n" ); document.write( "

Algebra.Com's Answer #776187 by mananth(16946) $\"\"$ $\"About$

You can put this solution on YOUR website!
let speed of train be x kmh
\n" ); document.write( "speed of car will be x-40 kmh\r
\n" ); document.write( "\n" ); document.write( "t= d/s\r
\n" ); document.write( "\n" ); document.write( "Time taken by car - time taken by train = 1/2\r
\n" ); document.write( "\n" ); document.write( "120/(x-40) -120/x = 1/2 hour\r
\n" ); document.write( "\n" ); document.write( "Find LCD and simplify\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "120x -120x+(120)(40) = (1/2)x(x-40)\r
\n" ); document.write( "\n" ); document.write( "4800 = (1/2)(x^2-40x)\r
\n" ); document.write( "\n" ); document.write( "9600 = x^2-40x\r
\n" ); document.write( "\n" ); document.write( "x^2-40x-9600 =0\r
\n" ); document.write( "\n" ); document.write( "x^2-120x+80x-9600=0\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "(x-120)(x+80)=0\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x= 120 kmph\r
\n" ); document.write( "\n" ); document.write( "Speed of train 120 kmph
\n" ); document.write( "Speed of car = 80 kmph\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

\n" );