A stationery box sells for 5 yuan. If Xiaodong buys this stationery box, the ratio of money between Xiaodong and Xiaopeng is 2:5. If Xiaopeng buys this stationery, the ratio of money between Xiaodong and Xiaopeng The ratio is 8:13, how much money does Xiaodong have?
一个文具盒卖价5元，如果小东买了这个文具盒，小东与小鹏的钱数之比是2：5，如果小鹏买了这个文具，则小东与小鹏的钱数之比是8：13，小东原来有多少钱？
<gadget id="calculator">8 + 13</gadget>
<output>21</output>

<gadget id="calculator">8 / 21</gadget>
<output>8/21 = around 0.380952</output>

<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(8/21) - (2/7)</gadget>
<output>2/21 = around 0.095238</output>

<gadget id="calculator">5 / (2/21)</gadget>
<output>105/2 = around 52.5</output>

<gadget id="calculator">(105/2) * (8/21)</gadget>
<output>20</output>

<result>20</result>