document.write( "Question 1126929: the length of a rectangle is 4 times the width and the perimeter is 30. How can I show my son how I arrived At the answer \n" ); document.write( "

Algebra.Com's Answer #743262 by math_helper(2461) $\"\"$ $\"About$

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L = length
\n" ); document.write( "W = width\r
\n" ); document.write( "\n" ); document.write( "(1) L = 4W (from \"length is 4 times the width\")
\n" ); document.write( "(2) 2L + 2W = 30 (from perimeter info)\r
\n" ); document.write( "\n" ); document.write( "Substitute for L (=4W) from eq 1 into eq 2. I'll go step-by-step:
\n" ); document.write( "2(4W) + 2W = 30
\n" ); document.write( "8W + 2W = 30
\n" ); document.write( "10W = 30
\n" ); document.write( " W = 30/10 = 3
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\n" ); document.write( "W=3 implies L = 4*3 = 12 (using eq 1)
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\n" ); document.write( "ЧЧ
\n" ); document.write( "Answer: width is 3, length is 12
\n" ); document.write( "ЧЧ
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\n" ); document.write( "\n" ); document.write( "Check: 2L + 2W should be 30: 2(12) + 2(3) = 24 + 6 = 30 (ok)\r
\n" ); document.write( "\n" ); document.write( "(and L=4W is true b/c we used that fact to compute L from W, can always re-check: L=12=4*3 = 4W (ok))\r
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