document.write( "Question 107934: A person traveling 4 hr by plane and 25 hr by ship covers 1580 miles. If the speed of the plane had been one-half of the actual speed and the speed of the ship had been one-fourth greater, the person would have traveled only 1315 miles in the same length of time. Find the speeds of the plane and the ship. \n" ); document.write( "
Algebra.Com's Answer #78733 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! A person traveling 4 hr by plane and 25 hr by ship covers 1580 miles. If the speed of the plane had been one-half of the actual speed and the speed of the ship had been one-fourth greater, the person would have traveled only 1315 miles in the same length of time. Find the speeds of the plane and the ship. \n" ); document.write( ": \n" ); document.write( "Let x = speed of the plane \n" ); document.write( "Let y = speed of the ship \n" ); document.write( ": \n" ); document.write( "Write two distance equations; Distance = time * speed \n" ); document.write( ": \n" ); document.write( "\"Actual\" equation: \n" ); document.write( "4x + 25y = 1580 \n" ); document.write( ": \n" ); document.write( "The \"If\" equation: \n" ); document.write( ".5(4x) + 1.25(25y) = 1315 \n" ); document.write( "or \n" ); document.write( "2x + 31.25y = 1315 \n" ); document.write( ": \n" ); document.write( "Multiply the above equation by 2, subtract the \"actual\" equation \n" ); document.write( "4x + 62.5y = 2630 \n" ); document.write( "4x + 25.0y = 1580 \n" ); document.write( "------------------- subtracting eliminates x \n" ); document.write( "0x + 37.5y = 1050 \n" ); document.write( "y = 1050/37.5 \n" ); document.write( "y = 28 mph is the actual speed of the ship \n" ); document.write( ": \n" ); document.write( "Find x using the \"actual\" equation \n" ); document.write( "4x + 25(28) = 1580 \n" ); document.write( "4x + 700 = 1580 \n" ); document.write( "4x = 1580 - 700 \n" ); document.write( "x = 880/4 \n" ); document.write( "x = 220 mph is the actual speed of the plane\r \n" ); document.write( "\n" ); document.write( ": \n" ); document.write( ":\r \n" ); document.write( "\n" ); document.write( "Check solution using the \"IF\" equation \n" ); document.write( ".5(4*220) + 1.25(25*28) = \n" ); document.write( "440 + 875 = 1315 \n" ); document.write( " |