SOLUTION: 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

Algebra ->  Customizable Word Problem Solvers  -> Finance -> SOLUTION: 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      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 92135: 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 the stamps is $2.60. Find the number of 13 cent stamps in the collection.
Found 2 solutions by stanbon, scott8148:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
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 the stamps is $2.60. Find the number of 13 cent stamps in the collection.
---------------------
Let number of 5 cent stamps be "x" ; value of these is 5x cents
--------------
Number of 13 cent stamps is "2x-1" ; value of these is 13(2x-1)=26x-13 cents
-------------------------
Number of 18 cent stamps is "2x+4" ; value of these is 18(2x+4)=36x+72 cents
--------------------------
EQUATION:
value + value +value = 260 cents
5x + 26x-13 +36x+72 = 260
67x + 59 = 260
67x = 201
x = 3 (number of 5 cent stamps)
2x-1 = 5 (number of 13 cent stamps)
2x+4 = 10 (number of 18 cent stamps)
=======================
Cheers,
Stan H.

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
let t=13cent ... (t+1)/2=5cent ... t+5=18cent ... 13t+5((t+1)/2)+18(t+5)=260

multiplying by 2 gives 26t+5t+5+36t+180=520 ... 67t=335 ... t=5