document.write( "Question 1028172: today, the difference in age between a father and his son is 23 years. two years from now, the father's age will double the age of his son in two years' time. \n" ); document.write( "

Algebra.Com's Answer #643322 by josmiceli(19441) $\"\"$ $\"About$

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The difference in their ages never changes
\n" ); document.write( "Let $\"+a+\"$ = father's age now
\n" ); document.write( "Let $\"+b+\"$ = son's age now
\n" ); document.write( "-------------------------
\n" ); document.write( "(1) $\"+a+=+b+%2B+23+\"$
\n" ); document.write( "(2) $\"+a+%2B+2+=+2%2A%28+b+%2B+2+%29+\"$
\n" ); document.write( "------------------------
\n" ); document.write( "Substitute (1) into (2)
\n" ); document.write( "(2) $\"+b+%2B+23+%2B+2+=+2%2A%28+b+%2B+2+%29+\"$
\n" ); document.write( "(2) $\"+b+%2B+25+=+2b+%2B+4+\"$
\n" ); document.write( "(2) $\"+b+=+21+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+a+=+b+%2B+23+\"$
\n" ); document.write( "(1) $\"+a+=+21+%2B+23+\"$
\n" ); document.write( "(1) $\"+a+=+44+\"$
\n" ); document.write( "-------------------
\n" ); document.write( "The father is 44 now
\n" ); document.write( "The son is 21 now
\n" ); document.write( "-------------------
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+a+%2B+2+=+2%2A%28+b+%2B+2+%29+\"$
\n" ); document.write( "(2) $\"+44+%2B+2+=+2%2A%28+21+%2B+2+%29+\"$
\n" ); document.write( "(2) $\"+46+=+2%2A23+\"$
\n" ); document.write( "(2) $\"+46+=+46+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );