document.write( "Question 173635: Four numbers have a total of 92. The first number is twice the second number and the third number is 4 more than the sum of the first two. The fourth number is 3 less than the difference of the first two numbers. What are the numbers? \n" ); document.write( "
Algebra.Com's Answer #128489 by gonzo(654)\"\" \"About 
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let a,b,c,d = the numbers.
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\n" ); document.write( "a + b + c + d = 92
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\n" ); document.write( "first number is twice the second number:
\n" ); document.write( "a = 2b
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\n" ); document.write( "third number is 4 more than the sum of the first two:
\n" ); document.write( "c = a + b + 4
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\n" ); document.write( "fourth number is 3 less than the difference of the first two numbers.
\n" ); document.write( "d = a - b - 3
\n" ); document.write( "since a > b this would be positive.
\n" ); document.write( "it works this way.
\n" ); document.write( "if we chose b - a, the difference would be negative and the result would not work out.
\n" ); document.write( "the assumption here is that we are looking for the absolute value of the difference which makes the difference always positive.
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\n" ); document.write( "the rest is just a substitution for what we know.
\n" ); document.write( "we start with:
\n" ); document.write( "a + b + c + d = 92
\n" ); document.write( "since a = 2b, we substitute 2b for a to get:
\n" ); document.write( "2b + b + c + d = 92
\n" ); document.write( "since c = a + b + 4, we substitute a + b + 4 to get:
\n" ); document.write( "2b + b + a + b + 4 + d = 92
\n" ); document.write( "since a = 2b, we again substitute 2b for a to get:
\n" ); document.write( "2b + b + 2b + b + 4 + d = 92
\n" ); document.write( "since d = a - b - 3, e substitute a - b - 3 for d to get:
\n" ); document.write( "2b + b + 2b + b + 4 + (a - b - 3) = 92
\n" ); document.write( "since a = 2b, we again substitute 2b for a to get:
\n" ); document.write( "2b + b + 2b + b + 4 + (2b - b - 3) = 92
\n" ); document.write( "we remove parentheses to get:
\n" ); document.write( "2b + b + 2b + b + 4 + 2b - b - 3 = 92
\n" ); document.write( "we combine likes to get:
\n" ); document.write( "7b + 1 = 92
\n" ); document.write( "we subtract 1 from both sides of the equation to get:
\n" ); document.write( "7b = 91
\n" ); document.write( "we divide both sides of the equation by 7 to get:
\n" ); document.write( "b = 13
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\n" ); document.write( "since b = 13, then
\n" ); document.write( "a = 2b = 26
\n" ); document.write( "c = a + b + 4 = 26 + 13 + 4 = 43
\n" ); document.write( "d = a - b - 3 = 26 - 13 - 3 = 10
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\n" ); document.write( "all variables are:
\n" ); document.write( "a = 26
\n" ); document.write( "b = 13
\n" ); document.write( "c = 43
\n" ); document.write( "d = 10
\n" ); document.write( "-----
\n" ); document.write( "sum of these is 92 satisfying the equation a + b + c + d = 92
\n" ); document.write( "a = 2b is good since 26 is 2 * 13
\n" ); document.write( "c = a + b + 4 = 43 is good since 26 + 13 + 4 = 43
\n" ); document.write( "d = a - b - 3 is good since 26 - 13 - 3 = 10
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\n" ); document.write( "your answer is:
\n" ); document.write( "a = 26
\n" ); document.write( "b = 13
\n" ); document.write( "c = 43
\n" ); document.write( "d = 10
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