Mom bought 5,000 shares of a certain stock at a price of 6.4 yuan per share, and sold it at a price of 8 yuan per share three years later. In stock trading, no matter whether you buy or sell, you have to pay stamp duty at 0.1% of the transaction amount, and pay commission at 0.15%. How much profit did your mother make from this investment?
妈妈按每股6.4元的价钱买入某种股票5000股，三年后按每股8元的价钱卖出．在股票交易中，无论买卖都要按成交金额的0.1%缴纳印花税，按0.15%缴纳佣金，妈妈这次投资共获利多少元？
<gadget id="calculator">8 * 5_000</gadget>
<output>40_000</output>

<gadget id="calculator">6.4 * 5_000</gadget>
<output>32_000</output>

<gadget id="calculator">40_000 - 32_000</gadget>
<output>8_000</output>

<gadget id="calculator">0.1 / 100</gadget>
<output>0.001</output>

<gadget id="calculator">32_000 * 0.001</gadget>
<output>32</output>

<gadget id="calculator">0.15 / 100</gadget>
<output>0.0015</output>

<gadget id="calculator">32_000 * 0.0015</gadget>
<output>48</output>

<gadget id="calculator">40_000 * 0.001</gadget>
<output>40</output>

<gadget id="calculator">40_000 * 0.0015</gadget>
<output>60</output>

<gadget id="calculator">32 + 48 + 40 + 60</gadget>
<output>180</output>

<gadget id="calculator">8_000 - 180</gadget>
<output>7_820</output>

<result>7_820</result>