document.write( "Question 25612: A stamp collection consists of 5, 13, and 18 cent stamps. The number of 13 cent stamps is one less than twice the number of 5 cent stamps. The number of 18 cent stamps is five more than the number of 13 cent stamps. The total value of all stamps is $2.60. Find the number of 13 cent stamps in the collection. \n" ); document.write( "
Algebra.Com's Answer #13733 by Paul(988)\"\" \"About 
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Let the 5 cent stamps be x
\n" ); document.write( "Let the 13 cent stamps be y
\n" ); document.write( "Let the 18 cent stamps be z
\n" ); document.write( "y = 2x-1---->2x-y=1 (equation 1)
\n" ); document.write( "z = 2x-1+5-->2x-z=-4 (equation 2)
\n" ); document.write( "5x+13y+18z=260 (equation 3)
\n" ); document.write( "Eliminate z
\n" ); document.write( "to eliminate z multiply the second equation by 18
\n" ); document.write( "5x+13y+18z=260
\n" ); document.write( "36x-18z=-72
\n" ); document.write( "--------------
\n" ); document.write( "41x+13y=188 (set 1)
\n" ); document.write( "Multiply equation 1 by 13 and THEN add Set 1 by equation 1
\n" ); document.write( "41x+13y=188
\n" ); document.write( "26x-13y=13 (y eliminated)
\n" ); document.write( "67x=201
\n" ); document.write( "x=3
\n" ); document.write( "Solve for y
\n" ); document.write( "y=2(3)-1
\n" ); document.write( "y=5
\n" ); document.write( "z=2(3)-1+5
\n" ); document.write( "z=10\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Hence, there were 3 five cents stamp, 5 thirteen cent stamps, and 10 eighteen cent stamps.
\n" ); document.write( "Paul.
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