document.write( "Question 105795: A man is 30 years older than his son. In 17 years his son would be half his age. How old is his son? \n" ); document.write( "
Algebra.Com's Answer #76980 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
Write an equation for each statement:
\n" ); document.write( ":
\n" ); document.write( "A man is 30 years older than his son.
\n" ); document.write( "M = S + 30
\n" ); document.write( ":
\n" ); document.write( "\"In 17 years his son would be half his age.\"
\n" ); document.write( "(S+17) = .5(M + 17)
\n" ); document.write( "S + 17 = .5M + 8.5
\n" ); document.write( "S = .5M + 8.5 - 17
\n" ); document.write( "S = .5M - 8.5
\n" ); document.write( ":
\n" ); document.write( " How old is his son?
\n" ); document.write( "Substitute (S+30) for M in the above equation and do some basic algebra:
\n" ); document.write( "S = .5(S+30) - 8.5
\n" ); document.write( "S = .5s + 15 - 8.5
\n" ); document.write( "S - .5S = 6.5
\n" ); document.write( ".5S = 6.5
\n" ); document.write( "S = 13 yrs old is the son now
\n" ); document.write( "Then
\n" ); document.write( "M = 13 + 30 = 43 yrs old is the old man now
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check our solutions in the statement:
\n" ); document.write( "\"In 17 years his son would be half his age.\"
\n" ); document.write( "(13 + 17) = .5(43 + 17)
\n" ); document.write( "30 = .5(60); confirms our solutions
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Did I make this understandable to you? Any questions? \n" ); document.write( "
\n" );