SOLUTION: Owyn just bought some $.39, $.24, and $.13 stamps at the post office. The 100 stamps cost $33.40, and there were twice as many $.24 stamps in the sale as there were $.13 stamps. Ho
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-> SOLUTION: Owyn just bought some $.39, $.24, and $.13 stamps at the post office. The 100 stamps cost $33.40, and there were twice as many $.24 stamps in the sale as there were $.13 stamps. Ho
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Question 1109457: Owyn just bought some $.39, $.24, and $.13 stamps at the post office. The 100 stamps cost $33.40, and there were twice as many $.24 stamps in the sale as there were $.13 stamps. How many stamps of each denomination did Owyn buy? Answer by ikleyn(52915) (Show Source):
Let x be the number of the 13-cent stamps.
Then the number of the 24-cent stamps is 2x, and
the number of the 39-cent stamps is (100-2x-x) = (100-3x).
The "money equation" is
13x + 24*(2x) + 39*(100-3x) = 3340 cents.
13x + 48x + 3900 - 117x = 3340,
-56x = 3340 - 3900 = -560 ====> x = = 10.
Answer. 10 13-cent stamps; 20 24-cent stamps and 100-10-20 = 70 39-cent stamps.
Check. 10*13 + 20*24 + 70*39 = 3340 cents. ! Correct !
The lesson to learn from this solution.
This problem is reduced to a single equation in one unknown.
