document.write( "Question 174113: the four oldest people in Golden City lived a total of 384 years put together. The difference in ages for the youngest and the second oldest is 14. The second youngest is 3 years older than the youngest. The oldest is 20 years older than the average of the second and youngest. What are their ages? \n" ); document.write( "
Algebra.Com's Answer #129020 by gonzo(654)\"\" \"About 
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youngest = a
\n" ); document.write( "second youngest = b
\n" ); document.write( "second oldest = c
\n" ); document.write( "oldest = d
\n" ); document.write( "-----
\n" ); document.write( "all four lived a total of 384 years.:
\n" ); document.write( "a + b + c + d = 384
\n" ); document.write( "-----
\n" ); document.write( "difference in ages for the youngest and the second oldest is 14:
\n" ); document.write( "c - a = 14
\n" ); document.write( "-----
\n" ); document.write( "the second youngest is 3 years older than the youngest.
\n" ); document.write( "b = a + 3
\n" ); document.write( "-----
\n" ); document.write( "The oldest is 20 years older than the average of the second and youngest.
\n" ); document.write( "*****
\n" ); document.write( "question here is second what?
\n" ); document.write( "second youngest or second oldest.
\n" ); document.write( "i'll have to solve for both to see.
\n" ); document.write( "if second oldest, then:
\n" ); document.write( "d = (c+a)/2 + 20
\n" ); document.write( "if second youngest, then:
\n" ); document.write( "d = (b+a)/2 + 20
\n" ); document.write( "-----
\n" ); document.write( "equations you have to work with are:
\n" ); document.write( "a + b + c + d = 384
\n" ); document.write( "c = a + 14 (derived from c-a = 14)
\n" ); document.write( "b = a + 3
\n" ); document.write( "----
\n" ); document.write( "before we go any further, we will substitute:
\n" ); document.write( "a + 14 for c, and:
\n" ); document.write( "a + 3 for b
\n" ); document.write( "-----
\n" ); document.write( "a + b + c + d becomes:
\n" ); document.write( "a + a + 3 + a + 14 + d = 384
\n" ); document.write( "if we combine like terms, this equation becomes:
\n" ); document.write( "3*a + 17 + d = 384
\n" ); document.write( "-----
\n" ); document.write( "we have also:
\n" ); document.write( "d = (c+a)/2 + 20
\n" ); document.write( "or:
\n" ); document.write( "d = (b+a)/2 + 20
\n" ); document.write( "-----
\n" ); document.write( "we'll look at d = (b+a)/2 + 20 first.
\n" ); document.write( "we start with:
\n" ); document.write( "d = (b+a)/2 + 20
\n" ); document.write( "we substitute a+3 for b:
\n" ); document.write( "d = (a + 3 + a)/2 + 20
\n" ); document.write( "we combine like terms:
\n" ); document.write( "d = (2*a + 3)/2 + 20
\n" ); document.write( "we substitute for d in the total equation:
\n" ); document.write( "3*a + 17 + d = 384
\n" ); document.write( "becomes:
\n" ); document.write( "3*a + 17 + (2*a+3)/2 + 20 = 384
\n" ); document.write( "we combine like terms:
\n" ); document.write( "3*a + 37 + (2*a+3)/2 = 384
\n" ); document.write( "we multiply by 2 to remove fractions:
\n" ); document.write( "6*a + 74 + 2*a + 3 = 768
\n" ); document.write( "we combine like terms:
\n" ); document.write( "8*a + 77 = 768
\n" ); document.write( "we subtract 77 from both sides:
\n" ); document.write( "8*a = 768 - 77
\n" ); document.write( "we combine like terms:
\n" ); document.write( "8*a = 691
\n" ); document.write( "a = 86.375
\n" ); document.write( "-----
\n" ); document.write( "i was looking for an integer.
\n" ); document.write( "before going further, i'll try the second option.
\n" ); document.write( "that was:
\n" ); document.write( "d = (c+a)/2 + 20
\n" ); document.write( "-----
\n" ); document.write( "we start with:
\n" ); document.write( "d = (c+a)/2 + 20
\n" ); document.write( "we substitute for c:
\n" ); document.write( "d = (a + 14 + a)/2 + 20
\n" ); document.write( "we substitute for d in the total equation:
\n" ); document.write( "3*a + 17 + d = 384
\n" ); document.write( "becomes:
\n" ); document.write( "3*a + 17 + (2*a + 14)/2 + 20 = 384
\n" ); document.write( "we remove parentheses:
\n" ); document.write( "3*a + 17 + 2*a/2 + 14/2 + 20 = 384
\n" ); document.write( "we simplify:
\n" ); document.write( "3*a + 17 + a + 7 + 20 = 384
\n" ); document.write( "we combine like terms:
\n" ); document.write( "4*a + 44 = 384
\n" ); document.write( "we subtract 44 from both sides:
\n" ); document.write( "4*a = 384 - 44
\n" ); document.write( "we simplify:
\n" ); document.write( "4*a = 340
\n" ); document.write( "we divide both sides by 4
\n" ); document.write( "a = 340/4 = 85
\n" ); document.write( "-----
\n" ); document.write( "this option looks more promising so we'll pursue further.
\n" ); document.write( "we used the equation for:
\n" ); document.write( "The oldest is 20 years older than the average of the second OLDEST and youngest.
\n" ); document.write( "to solve for d:
\n" ); document.write( "d = (c+a)/2 + 20
\n" ); document.write( "-----
\n" ); document.write( "we have a = 85
\n" ); document.write( "c = a + 14 = 85 + 14 = 99
\n" ); document.write( "c = 99
\n" ); document.write( "-----
\n" ); document.write( "b = a + 3 = 85 + 3 = 88
\n" ); document.write( "b = 88
\n" ); document.write( "-----
\n" ); document.write( "d = (c+a)/2 + 20 = (99 + 85)/2 + 20 = 184/2 + 20 = 92 + 20 = 112
\n" ); document.write( "d = 112
\n" ); document.write( "-----
\n" ); document.write( "a = 85
\n" ); document.write( "-----
\n" ); document.write( "a + b + c + d = 85 + 88 + 99 + 112 = 384
\n" ); document.write( "-----
\n" ); document.write( "the equation appears to be satisfied.
\n" ); document.write( "youngest is 85
\n" ); document.write( "second youngest is 88
\n" ); document.write( "second oldest is 99
\n" ); document.write( "oldest is 112
\n" ); document.write( "-----
\n" ); document.write( "i also solved for:
\n" ); document.write( "d = (a+b)/2 + 20
\n" ); document.write( "which was:
\n" ); document.write( "The oldest is 20 years older than the average of the second YOUNGEST and youngest.
\n" ); document.write( "the answer came out different but i was still able to solve it and got an answer that also makes sense except that the ages are not in whole integers.
\n" ); document.write( "here's how that worked:
\n" ); document.write( "d = (a+b)/2 + 20
\n" ); document.write( "we substitute for b:
\n" ); document.write( "d = (a + a + 3)/2 + 20
\n" ); document.write( "we substitute for d in the total equation:
\n" ); document.write( "3*a + 17 + d = 384
\n" ); document.write( "becomes:
\n" ); document.write( "3*a + 17 + (2*a + 3)/2 + 20 = 384
\n" ); document.write( "we combine like terms:
\n" ); document.write( "3*a + 37 + (2*a + 3)/2 = 384
\n" ); document.write( "we subtract 37 from both sides:
\n" ); document.write( "3*a + (2*a + 3)/2 = 347
\n" ); document.write( "we multiply both sides by 2 to get:
\n" ); document.write( "6*a + 2*a + 3 = 2*347
\n" ); document.write( "we combine like terms and simplify:
\n" ); document.write( "8*a + 3 = 694
\n" ); document.write( "we subtract 3 from both sides:
\n" ); document.write( "8*a = 691
\n" ); document.write( "we divide both sides by 8:
\n" ); document.write( "a = 691/8 = 86.375
\n" ); document.write( "b = a + 3 = 89.375
\n" ); document.write( "c = a + 14 = 100.375
\n" ); document.write( "d = (a+b)/2 + 20 = (86.375 + 89.375)/2 + 20 = 175.75/2 + 20 =87.875 + 20 = 107.875
\n" ); document.write( "-----
\n" ); document.write( "we have:
\n" ); document.write( "a = 86.375
\n" ); document.write( "b = 89.375
\n" ); document.write( "c = 100.375
\n" ); document.write( "d = 107.875
\n" ); document.write( "add them all up together and we get:
\n" ); document.write( "384
\n" ); document.write( "-----
\n" ); document.write( "whether we used second oldest or second youngest in solving for d, we had a solution either way.
\n" ); document.write( "-----
\n" ); document.write( "choose the one that applies to your problem.
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