document.write( "Question 505176: Tony is 5 years older than his sister. In 3 years he will be twice as oldas she is. How old is Tony?
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Algebra.Com's Answer #339804 by Maths68(1474)\"\" \"About 
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Let
\n" ); document.write( "Present age of Tony = t
\n" ); document.write( "Present age of Sister = s
\n" ); document.write( "Tony is 5 years older means if we add 5 to present age of his sister both will be of equal age
\n" ); document.write( "t=s+5 ..........(1)
\n" ); document.write( "In three years means we have to add 3 in the present ages of both
\n" ); document.write( "t+3=s+3
\n" ); document.write( "then he will be twice as old as his sister
\n" ); document.write( "t+3=2(s+3)
\n" ); document.write( "t+3=2s+6
\n" ); document.write( "t=2s+6-3
\n" ); document.write( "t=2s+3
\n" ); document.write( "Put the value of t in from (1) to above equation
\n" ); document.write( "s+5=2s+3
\n" ); document.write( "s=2s+3-5
\n" ); document.write( "s-2s=3-5
\n" ); document.write( "-s=-2
\n" ); document.write( "Multiply by (-1) both sides of the equation
\n" ); document.write( "(-1)(-s)=(-2)(-1)
\n" ); document.write( "s=2
\n" ); document.write( "Put the value of s in (1), we have
\n" ); document.write( "t=s+5 ..........(1)
\n" ); document.write( "t=2+5
\n" ); document.write( "t=7\r
\n" ); document.write( "\n" ); document.write( "Present age of Tony = t = 7 years old
\n" ); document.write( "Present age of Sister = s = 2 years old
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