F.1 Math(急!!! 20點!!!)幫幫忙!!!!!!

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以下是問題:

Ken has a total of 36 stamps with face value either $13 or $5 each.
Given that the total value of the stamps is $300,
find the respective number of $13 and $5 stamps.

翻譯:
Ken 一共有36個 stamps , 當中有 $13 and $5的 stamps
總共加起上來有 $300
find $13 and $5 的 stamps 分別有幾多個

急!!!!!!!!!!!!
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