document.write( "Question 460300: A car was driven for 2 hours part of the time at 40 miles per hour and the rest of the time at 60 miles per hour. the total distance was 90 miles . how long did the car travel at each speed. \n" ); document.write( "

Algebra.Com's Answer #315726 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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A car was driven for 2 hours part of the time at 40 miles per hour and the rest of the time at 60 miles per hour.
\n" ); document.write( " the total distance was 90 miles . how long did the car travel at each speed.
\n" ); document.write( ":
\n" ); document.write( "Let x = distance at 40 mph
\n" ); document.write( "then
\n" ); document.write( "(90-x) = distance at 60 mph
\n" ); document.write( ":
\n" ); document.write( "Write a time equation; time = dist/speed
\n" ); document.write( ":
\n" ); document.write( "4o mph time + 60 mph time = 2 hrs
\n" ); document.write( " $\"x%2F40\"$ + $\"%28%2890-x%29%29%2F60\"$ = 2
\n" ); document.write( "Multiply by 120
\n" ); document.write( "120* $\"x%2F40\"$ + 120* $\"%28%2890-x%29%29%2F60\"$ = 120(2)
\n" ); document.write( "Cancel the denominators and you have:
\n" ); document.write( "3x + 2(90-x) = 240
\n" ); document.write( "3x + 180 - 2x = 240
\n" ); document.write( "3x - 2x = 240 - 180
\n" ); document.write( "x = 60 mi at 40 mph
\n" ); document.write( "then
\n" ); document.write( "90-60 = 30 mi at 60 mph
\n" ); document.write( ":
\n" ); document.write( "Find the times at each speed
\n" ); document.write( "60/40 = 1.5 hr at 40 mph
\n" ); document.write( "30/60 = .5 hrs at 60 mph
\n" ); document.write( "--------------
\n" ); document.write( "total 2 hrs \n" ); document.write( "

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