document.write( "Question 845178: AN AIRPLANE AT 19,200 FEET IS DESCENDING AT A RATE OF 40 FEET PER SECOND ANOTHER AIRPLANE TAKES OFF AND ASCENDS AT A RATE OF 60 FEET PER SECOND AFTER HOW MANY SECONDS WILL THE AIRPLANES BE AT THE Same height what is the height \n" ); document.write( "
Algebra.Com's Answer #509323 by ankor@dixie-net.com(22740)\"\" \"About 
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AN AIRPLANE AT 19,200 FEET IS DESCENDING AT A RATE OF 40 FEET PER SECOND ANOTHER AIRPLANE TAKES OFF AND ASCENDS AT A RATE OF 60 FEET PER SECOND AFTER
\n" ); document.write( " HOW MANY SECONDS WILL THE AIRPLANES BE AT THE Same height what is the height
\n" ); document.write( ":
\n" ); document.write( "Write an equation for each plane,
\n" ); document.write( "let t = flying time in seconds for each plane
\n" ); document.write( "Descending: h = 19200 - 40t
\n" ); document.write( "Ascending: h = 60t
\n" ); document.write( ":
\n" ); document.write( "h = h, therefore
\n" ); document.write( "60t = 19200-40t
\n" ); document.write( "60t + 40t = 19200
\n" ); document.write( "100t = 19200
\n" ); document.write( "t = 19200/100
\n" ); document.write( "t = 192 seconds
\n" ); document.write( ":
\n" ); document.write( "Find the height:
\n" ); document.write( "h = 19200 - 192(40)
\n" ); document.write( "h = 19200 - 7680
\n" ); document.write( "h = 11,520 ft
\n" ); document.write( ":
\n" ); document.write( "Check the height
\n" ); document.write( "h = 192(60)
\n" ); document.write( "h = 11,520 ft \n" ); document.write( "
\n" );