document.write( "Question 1048832: Gary is as old as Harry will be when Gary is twice as old as Harry was when Gary’s age was half the sum of their present ages. \r
\n" ); document.write( "\n" ); document.write( "Harry is as old as Gary was when Harry was half the age he will be 10 years from now. \r
\n" ); document.write( "\n" ); document.write( "What is Harry’s age?
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Algebra.Com's Answer #664391 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
Let \"+g+\" = Gary's age now
\n" ); document.write( "Let \"+h+\" = Harry's age now
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\n" ); document.write( "With these types of problems, I start at
\n" ); document.write( "the end of a statement.
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\n" ); document.write( "\"when Gary’s age was half the sum of their present ages.\"
\n" ); document.write( "Gary's age was \"+%28+g+%2B+h+%29%2F2+\"
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\n" ); document.write( "\"as Harry was when Gary’s age was half the sum of their present ages.\"
\n" ); document.write( "Harry was what was Gary's age then plus the difference in
\n" ); document.write( "their ages ( I'm assuming Harry is the older one )
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\n" ); document.write( "Harry's age was \"+%28+g+%2B+h+%29+%2F+2+%2B+%28+h+-+g+%29+\"
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\n" ); document.write( "\"when Gary is twice as old as Harry was when Gary’s
\n" ); document.write( "age was half the sum of their present ages.\"
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\n" ); document.write( "This is when Gary is:
\n" ); document.write( "\"+2%2A%28+%28+g%2Bh+%29%2F2+%2B+%28+h-g+%29+%29+\"
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\n" ); document.write( "\"as Harry will be when Gary is twice as old as Harry was
\n" ); document.write( "when Gary’s age was half the sum of their present ages.
\n" ); document.write( "This means I have to add the difference in their ages again
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\n" ); document.write( "Harry will be:
\n" ); document.write( "\"+2%2A%28+%28+g%2Bh+%29%2F2+%2B+%28+h-g+%29+%29+%2B+%28+h-g+%29+\"
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\n" ); document.write( "I am told that Gary is presently this age, so I can say:
\n" ); document.write( "(1) \"+g+=+2%2A%28+%28+g%2Bh+%29%2F2+%2B+%28+h-g+%29+%29+%2B+%28+h-g+%29+\"
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\n" ); document.write( "Reading the 2nd statement:
\n" ); document.write( "\"when Harry was half the age he will be 10 years from now.\"
\n" ); document.write( "Harry was:
\n" ); document.write( "\"+%281%2F2%29%2A%28+h+%2B+10+%29+\"
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\n" ); document.write( "\"as Gary was when Harry was half
\n" ); document.write( "the age he will be 10 years from now.\"
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\n" ); document.write( "Gary was the younger, so I will subtract the difference in their ages
\n" ); document.write( "\"+%281%2F2%29%2A%28+h+%2B+10+%29+-+%28+h-g+%29+\"
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\n" ); document.write( "This is Harry's age now, so I can say:
\n" ); document.write( "(2) \"+h+=+%281%2F2%29%2A%28+h%2B10+%29+-+%28+h-g+%29+\"
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\n" ); document.write( "(1) \"+g+=+2%2A%28+%28+g%2Bh+%29%2F2+%2B+%28+h-g+%29+%29+%2B+%28+h-g+%29+\"
\n" ); document.write( "(1) \"+g+=+%28+g%2Bh+%29+%2B+2%2A%28+h+-+g+%29+%2B+%28+h-g+%29+\"
\n" ); document.write( "(1) \"+g+=+g+%2B+h+%2B+2h+-+2g+%2B+h+-+g+\"
\n" ); document.write( "(1) \"+g+=+-2g+%2B+4h+\"
\n" ); document.write( "(1) \"+3g+=+4h+\"
\n" ); document.write( "(1) \"+h+=+%283%2F4%29%2Ag+\"
\n" ); document.write( "( It seems that Harry was actually younger )
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\n" ); document.write( "(2) \"+h+=+%281%2F2%29%2A%28+h%2B10+%29+-+%28+h-g+%29+\"
\n" ); document.write( "(2) \"+2h+=+h+%2B+10+-2%2A%28+h-g+%29+\"
\n" ); document.write( "(2) \"+h+=+10+-+2h+%2B+2g+\"
\n" ); document.write( "(2) \"+3h+=+2g+%2B+10+\"
\n" ); document.write( "(2) \"+2g+=+3h+-+10+\"
\n" ); document.write( "(2) \"+g+=+%283%2F2%29%2Ah+-+5+\"
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\n" ); document.write( "By substitution:
\n" ); document.write( "(1) \"+h+=+%283%2F4%29%2A%28%28+3%2F2%29%2Ah+-+5+%29+\"
\n" ); document.write( "(1) \"+4h+=+3%2A%283%2F2%29%2Ah+-+20+\"
\n" ); document.write( "(1) \"+8h+=+9h+-+40+\"
\n" ); document.write( "(1) \"+h+=+40+\"
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\n" ); document.write( "Harry is 40
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\n" ); document.write( "check:
\n" ); document.write( "(2) \"+g+=+%283%2F2%29%2Ah+-+5+\"
\n" ); document.write( "(2) \"+g+=+%283%2F2%29%2A40+-+5+\"
\n" ); document.write( "(2) \"+g+=+60+-+5+\"
\n" ); document.write( "(2) \"+g+=+55+\"
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\n" ); document.write( "You can go back to the start and try
\n" ); document.write( "to prove this step by step. I'm too
\n" ); document.write( "tired. Hope I got it right!
\n" ); document.write( "Get a 2nd opinion if you like.\r
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