document.write( "Question 953752: when the son will be as old as his father today, the sum of their ages will be 126.when the father was as old as his son today, the sum of their ages then was 38.Find their present ages
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Algebra.Com's Answer #582544 by ankor@dixie-net.com(22740)\"\" \"About 
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when the son will be as old as his father today, the sum of their ages will be 126.when the father was as old as his son today, the sum of their ages then was 38.Find their present ages
\n" ); document.write( "Find their present ages
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\n" ); document.write( "let f = father's age
\n" ); document.write( "let s = son's age
\n" ); document.write( "let d = f - s, their age difference
\n" ); document.write( ":
\n" ); document.write( "\"when the son will be as old as his father today, the sum of their ages will be 126.\"
\n" ); document.write( "(s+d) + (f+d) = 126
\n" ); document.write( "s + f + 2d = 126
\n" ); document.write( "replace d with (f-s)
\n" ); document.write( "s + f + 2(f-s) = 126
\n" ); document.write( "s + f + 2f - 2s = 126
\n" ); document.write( "3f - s = 126
\n" ); document.write( ":
\n" ); document.write( "\"when the father was as old as his son today, the sum of their ages then was 38.\"
\n" ); document.write( "(f-d) + (s-d) = 38
\n" ); document.write( "s + f - 2d = 38
\n" ); document.write( "replace d with (f-s)
\n" ); document.write( "s + f - 2(f-s) = 38
\n" ); document.write( "s + f - 2f + 2s = 38
\n" ); document.write( "-f + 3s = 38
\n" ); document.write( ":
\n" ); document.write( "Use elimination here, multiply the above equation by 3, add to the 1st eq
\n" ); document.write( "-3f + 9s = 114
\n" ); document.write( "+3f - s = 126
\n" ); document.write( "---------------Adding eliminates f, find s
\n" ); document.write( "8s = 230
\n" ); document.write( "s = 240/8
\n" ); document.write( "s = 30 yrs is the son's age
\n" ); document.write( "Find Dad's age using equation 3f -s = 126
\n" ); document.write( "3f -30 = 126
\n" ); document.write( "3f = 126 + 30
\n" ); document.write( "3f = 156
\n" ); document.write( "f = 156/3
\n" ); document.write( "f = 52 yrs is Father's age
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\n" ); document.write( "Confirm this in the statement (there is a 22 yr difference in age):
\n" ); document.write( "when the son will be as old as his father today, the sum of their ages will be 126.\"
\n" ); document.write( "30 + 22 + 52 + 22 = 126\r
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