document.write( "Question 334997: Five years ago, John was three times older than Jack. Today, John is just twice as old as Jack. How old is John today? How old was Jack 5 years ago? \n" ); document.write( "
Algebra.Com's Answer #240168 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
Let n = John's present age
\n" ); document.write( "Let k = Jack's present age
\n" ); document.write( ":
\n" ); document.write( "Write an equation for each statement and simplify:
\n" ); document.write( ":
\n" ); document.write( "Five years ago, John was three times older than Jack.\"
\n" ); document.write( "n - 5 = 3(k-5)
\n" ); document.write( "n - 5 = 3k - 15
\n" ); document.write( "n = 3k - 15 + 5
\n" ); document.write( "n = 3k - 10
\n" ); document.write( ":
\n" ); document.write( "Today, John is just twice as old as Jack.
\n" ); document.write( "n = 2k
\n" ); document.write( ":
\n" ); document.write( " How old is John today?
\n" ); document.write( "Replace n with 2k in the 1st simplified equation
\n" ); document.write( "2k = 3k - 10
\n" ); document.write( "2k - 3k = -10
\n" ); document.write( "-k = -10
\n" ); document.write( "k = 10 yrs is Jack's age today
\n" ); document.write( "then
\n" ); document.write( "2(10) = 20 yrs is John's present age
\n" ); document.write( ";
\n" ); document.write( "How old was Jack 5 years ago
\n" ); document.write( "10 - 5 = 5 yrs is Jack's age 5 yrs ago
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check solution in the statement:
\n" ); document.write( "\"Five years ago, John was three times older than Jack. \"
\n" ); document.write( "20 - 5 = 3(10 - 5); confirms our solutions \n" ); document.write( "
\n" );