document.write( "Question 1143006: Two bond funds pay interest at rates that differ by 4%. Money invested for one year in the first fund earns $420 interest. The same amount invested in the other fund earns $560. Find the lower rate of interest \n" ); document.write( "
Algebra.Com's Answer #763753 by Theo(13342)\"\" \"About 
You can put this solution on YOUR website!
let x = the lower rate of interest.
\n" ); document.write( "then x + 4%/100 = the higher rate of interest.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "let y equal the investment.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "your two equations are:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x * y = 420
\n" ); document.write( "(x + .04) * y = 560\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "solve for y in the first equation to get y = 420/x
\n" ); document.write( "replace y with that in the second equation to get (x + .04) * 420/x = 560
\n" ); document.write( "multiply both sides of that equation by x to get (x + .04) * 420 = 560 * x
\n" ); document.write( "simplify to get 420 * x + .04 * 420 = 560 * x
\n" ); document.write( "subtract 420 * x from both sides of the equation to get .04 * 420 = 140 * x
\n" ); document.write( "divide both sides of the equation by 140 to get .04 * 420 / 140 = x
\n" ); document.write( "solve for x to get x = .12\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x * y = 420 becomes .12 * y = 420
\n" ); document.write( "solve for y to get y = 420 / .12 = 3500\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "(x + 4) * y = 560 becomes .16 * y = 560
\n" ); document.write( "solve for y to get y = 560 / .16 = 3500\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "the lower rate of interest = .12 = 12%.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
\n" );