document.write( "Question 517385: Jason is 21 years older than his sister Sarah. In 5 years he will be twice as old as Sarah. How old is each of them now? \n" ); document.write( "
Algebra.Com's Answer #344849 by Maths68(1474)\"\" \"About 
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Let
\n" ); document.write( "Present age of Jason = j
\n" ); document.write( "Present age of Sarah = s\r
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\n" ); document.write( "\n" ); document.write( "Jason is 21 years older than his sister Sarah.
\n" ); document.write( "j=s+21.............(1)
\n" ); document.write( "In 5 years their age will be
\n" ); document.write( "j+5=s+5
\n" ); document.write( "then he will be twice as old as Sarah.
\n" ); document.write( "j+5=2(s+5)
\n" ); document.write( "j+5=2s+10
\n" ); document.write( "j=2s+10-5
\n" ); document.write( "j=2s+5..............(2)
\n" ); document.write( "Put the value of j from (1) to (2)
\n" ); document.write( "s+21=2s+5
\n" ); document.write( "s-2s=5-21
\n" ); document.write( "-s=-16
\n" ); document.write( "Multiply by -1 both sides
\n" ); document.write( "s=16
\n" ); document.write( "Put the value of s in (1)
\n" ); document.write( "j=s+21
\n" ); document.write( "j=16+21
\n" ); document.write( "j=37
\n" ); document.write( "Present age of Jason = j = 37 years old
\n" ); document.write( "Present age of Sarah = s = 16 years old
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