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Mary is now twice as old as Jabe.Seven years ago, the sum of their ages was 16.What are their ages now and seven years ago?
\n" ); document.write( " Mary now-
\n" ); document.write( " Jabe now-
\n" ); document.write( " Mary 7 years ago-
\n" ); document.write( " Jabe 7 years ago- \r
\n" ); document.write( "\n" ); document.write( "Let Mary be M yrs old now
\n" ); document.write( "and let Jabe be J yrs old now
\n" ); document.write( "Mary is now twice as old as Jabe
\n" ); document.write( "That is M = 2J ----(1)
\n" ); document.write( "Seven years ago, the sum of their ages was 16
\n" ); document.write( "7 yrs ago
\n" ); document.write( "Mary was (M-7) yrs old
\n" ); document.write( "and Jabe was (J-7) yrs old.
\n" ); document.write( "And then the sum of their ages was 16
\n" ); document.write( "Therefore [(M-7) + (J-7)] = 16
\n" ); document.write( "M+J -7-7 = 16
\n" ); document.write( "M+J-14 = 16
\n" ); document.write( "M+J = 16+14
\n" ); document.write( "M+J = 30 ----(2)
\n" ); document.write( "using(1), M = 2J
\n" ); document.write( "2J+J = 30
\n" ); document.write( "3J = 30
\n" ); document.write( "J = 30/3 = 10
\n" ); document.write( "J=10 in (1)
\n" ); document.write( "M= 2J = 2X10 = 20
\n" ); document.write( "Answer: Mary's present age is 20 yrs
\n" ); document.write( "and Jabe's present age is 10 yrs
\n" ); document.write( "Seven yrs ago
\n" ); document.write( "Mary was (20-7) = 13 yrs
\n" ); document.write( "and Jabe was (10-7) = 3 yrs
\n" ); document.write( "Verification: The sum of their ages 7 yrs ago is 13+3 = 16 which is correct\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "