document.write( "Question 536716: Over a distance of 240km, the average speed of a train is 20km/h faster than that of a car. It takes the car 30 minutes longer to cover the same distance. What is the speed of the car and the speed of the train?\r
\n" ); document.write( "\n" ); document.write( "Thank you for any help:) \n" ); document.write( "
Algebra.Com's Answer #352550 by mananth(16946)\"\" \"About 
You can put this solution on YOUR website!
speed of car = x
\n" ); document.write( "speed of train = x+20\r
\n" ); document.write( "\n" ); document.write( "d=240
\n" ); document.write( "t=d/r\r
\n" ); document.write( "\n" ); document.write( "time car - time train = 1/2 hour\r
\n" ); document.write( "\n" ); document.write( "(240/x)-240/(x+20)=1/2\r
\n" ); document.write( "\n" ); document.write( "LCD = x(x+20)\r
\n" ); document.write( "\n" ); document.write( "240(x+20)-240x= x(x+20)/2
\n" ); document.write( "240x+4800-240x=(x^2+20x)/2
\n" ); document.write( "9600=x^2+20x\r
\n" ); document.write( "\n" ); document.write( "x^2+20x-9600=0\r
\n" ); document.write( "\n" ); document.write( "Find the roots of the equation by quadratic formula
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\n" ); document.write( "a= 1 ,b= 20 ,c= -9600
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\n" ); document.write( "b^2-4ac= 400 + 38400
\n" ); document.write( "b^2-4ac= 38800
\n" ); document.write( "\"x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29\"
\n" ); document.write( "\"x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29\"
\n" ); document.write( "\"x1=%28-12%2B21%29%2F%2812%29\"
\n" ); document.write( "x1=( -20 + 196.98 )/ 2
\n" ); document.write( "x1= 88.49 88 43/88
\n" ); document.write( "x2=( -20 -196.98 ) / 2
\n" ); document.write( "x2= -108.49
\n" ); document.write( "Ignore negative value
\n" ); document.write( "car speed = 88.49 mph
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