document.write( "Question 174725: the sum of the digits of a two-digit number is 10. If the digits are reversed, the number is increased by 72. What is the original number? \n" ); document.write( "

Algebra.Com's Answer #129779 by Mathtut(3670) $\"\"$ $\"About$

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let the two digits be a and b
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\n" ); document.write( "a+b=10..........eq 1
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\n" ); document.write( "10b+a=10a+b+72--->9a-9b=-72..eq 2
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\n" ); document.write( "re write eq 1 to a=10-b and plug it into eq 2
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\n" ); document.write( "9(10-b)-9b=-72
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\n" ); document.write( "90-9b-9b=-72
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\n" ); document.write( "-18b=-162
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\n" ); document.write( " $\"highlight%28b=9%29\"$
\n" ); document.write( " $\"highlight%28a=10-9=1%29\"$
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\n" ); document.write( "original number $\"highlight%28ab=19%29\"$ \r
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