The farm raises 500 white pigs and black pigs in total, and the white pigs account for (2/5). Later, a batch of white pigs are purchased, and the white pigs account for (2/3). How many white pigs are purchased?
饲养场养了白猪、黑猪共500头，白猪占(2/5)，后来又购进一批白猪，这时白猪占(2/3)，购进多少头白猪．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">500 * (2/3)</gadget>
<output>1_000/3 = around 333.333333</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">500 * (2/5)</gadget>
<output>200</output>

<gadget id="calculator">500 - 500 - 200</gadget>
<output>-200</output>

<gadget id="calculator">(1_000/3) + (-200)</gadget>
<output>400/3 = around 133.333333</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(400/3) / (1/3)</gadget>
<output>400</output>

<result>400</result>