document.write( "Question 774061: Sarah is 1/7 as old as Donald. In 9 years, Sarah's age will be 6 years more than 1/6 of Donald's age. How old are Sarah and Donald now? \n" ); document.write( "

Algebra.Com's Answer #472028 by DrBeeee(684) $\"\"$ $\"About$

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Let s = Sarah's current age
\n" ); document.write( "Let d = Donald's current age
\n" ); document.write( "The at present we have
\n" ); document.write( "(1) s = d/7
\n" ); document.write( "And in 9 years we have
\n" ); document.write( "(2) s + 9 = 6 + (d+9)/6 or
\n" ); document.write( "(3) s +3 = d/6 + 9/6 or
\n" ); document.write( "(4) s + 3/2 = d/6
\n" ); document.write( "Now substitute s of (1) into (4) and get
\n" ); document.write( "(5) d/7 + 3/2 = d/6 or
\n" ); document.write( "(6) d/6 - d/7 = 3/2 or
\n" ); document.write( "(7) (7-6)d/42 = 3/2 or
\n" ); document.write( "(8) d = 42*(3/2) or
\n" ); document.write( "(9) d = 21*3 or
\n" ); document.write( "(10) d = 63
\n" ); document.write( "Using (1) we get
\n" ); document.write( "(11) s = 63/7 or
\n" ); document.write( "(12) s = 9
\n" ); document.write( "Let's check these values with (2).
\n" ); document.write( "Is (9 + 9 = 6 + (63+9)/6)?
\n" ); document.write( "Is (18 = 6 + 72/6)?
\n" ); document.write( "Is (18 = 6 + 12)?
\n" ); document.write( "Is (18 = 18)? Yes.
\n" ); document.write( "Answer: Currently Sarah is 9 and Donald is 63. \n" ); document.write( "

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