document.write( "Question 638661: The sum of a fathers age and his son son's age is 100 years. Also, one-tenth of the product of their ages, in years exceeds the father's age by 180. How old is the son ? \n" ); document.write( "
Algebra.Com's Answer #402325 by mananth(16946)\"\" \"About 
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Father's age =x
\n" ); document.write( "son's age = y\r
\n" ); document.write( "\n" ); document.write( "x+y = 100
\n" ); document.write( "x= 100-y\r
\n" ); document.write( "\n" ); document.write( "According to the second condition\r
\n" ); document.write( "\n" ); document.write( "(1/10) xy = x+180
\n" ); document.write( "xy= 10(x+180)
\n" ); document.write( "xy = 10x+1800
\n" ); document.write( "xy-10x=1800
\n" ); document.write( "x(y-10)=1800
\n" ); document.write( "x= 1800/(y-10)\r
\n" ); document.write( "\n" ); document.write( "100-y= 1800/(y-10)\r
\n" ); document.write( "\n" ); document.write( "(100-y)(y-10)=1800
\n" ); document.write( "100y-1000-y^2+10y=1800\r
\n" ); document.write( "\n" ); document.write( "y^2-110y+2800 =0\r
\n" ); document.write( "\n" ); document.write( "y^2-70y-40y+2800=0
\n" ); document.write( "y(y-70)-40(y-70)=0
\n" ); document.write( "(y-70)(y-40)=0\r
\n" ); document.write( "\n" ); document.write( "y= 70 OR 40\r
\n" ); document.write( "\n" ); document.write( "x+y = 100
\n" ); document.write( "son's age cannot be more than father's age
\n" ); document.write( "so y = 40
\n" ); document.write( "Son's age = 40 years
\n" ); document.write( "Fathers age = 60 years\r
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