document.write( "Question 567574: The sum of the digits of a two digit number is 9. If the digits are reversed, the number formed bears the ratio 3:8 to the original number. Find the original number (Ans. 77) \n" ); document.write( "
Algebra.Com's Answer #366616 by josmiceli(19441)\"\" \"About 
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let the tens digit = \"+a+\"
\n" ); document.write( "Let the units digit = \"+b+\"
\n" ); document.write( "The actual number is \"+10a+%2B+b+\"
\n" ); document.write( "The number with the digits reversed is \"+10b+%2B+a+\"
\n" ); document.write( "given:
\n" ); document.write( "(1) \"+a+%2B+b+=+9+\"
\n" ); document.write( "(2) \"+%28+10b+%2B+a+%29+%2F+%28+10a+%2B+b+%29+=+3%2F8+\"
\n" ); document.write( "------------
\n" ); document.write( "Multiply both sides of (2) by \"+8%2A%28+10a+%2B+b+%29+\"
\n" ); document.write( "(2) \"+8%2A%2810b+%2B+a%29+=+3%2A%28+10a+%2B+b+%29+\"
\n" ); document.write( "(2) \"+80b+%2B+8a+=+30a+%2B+3b+\"
\n" ); document.write( "(2) \"+22a+-+77b+=+0+\"
\n" ); document.write( "(2) \"+22a+=+77b+\"
\n" ); document.write( "(2) \"+a+=+%2877%2F22%29%2Ab+\"
\n" ); document.write( "(2) \"+a+=+%287%2F2%29%2Ab+\"
\n" ); document.write( "Substitute (2) into (1)
\n" ); document.write( "(1) \"+%287%2F2%29%2Ab+%2B+b+=+9+\"
\n" ); document.write( "(1) \"+7b+%2B+2b+=+18+\"
\n" ); document.write( "(1) \"+9b+=+18+\"
\n" ); document.write( "(1) \"+b+=+2+\"
\n" ); document.write( "and, since
\n" ); document.write( "(1) \"+a%2B+b+=+9+\"
\n" ); document.write( "(1) \"+a+%2B+2+=+9+\"
\n" ); document.write( "(1) \"+a+=+7+\"
\n" ); document.write( "The original number is 72
\n" ); document.write( "check answer:
\n" ); document.write( "(2) \"+%28+10b+%2B+a+%29+%2F+%28+10a+%2B+b+%29+=+3%2F8+\"
\n" ); document.write( "(2) \"+%28+10%2A2+%2B+7+%29+%2F+%28+10%2A7+%2B+2+%29+=+3%2F8+\"
\n" ); document.write( "(2) \"+27+%2F+72+=+3%2F8+\"
\n" ); document.write( "Multiply both sides by \"+72+\"
\n" ); document.write( "(2) \"+27+=+3%2A9+\"
\n" ); document.write( "(2) \"+27+=+27+\"
\n" ); document.write( "OK
\n" ); document.write( "Note that the answer \"+77+\" is impossible,
\n" ); document.write( "since the digits have to add up to \"9\"
\n" ); document.write( "
\n" );