Xiao Ming bought a batch of cloth shoes at a price of 6.5 yuan per pair, and sold them at a price of 8.7 yuan per pair. As of today, only (1/4) is left, and Xiao Ming has recovered all the shoes he bought, and has made a profit of 20 yuan. How many pairs of this batch of cloth shoes do you want to buy?
小明以每双6.5元的价钱购进一批布鞋，又以每双8.7元的价钱卖出．到今天卖的只剩下(1/4)，小明已收回全部购鞋款，而且已获利20元．求购进的这批布鞋一共有多少双？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 8.7</gadget>
<output>2.175</output>

<gadget id="calculator">8.7 - 2.175 - 6.5</gadget>
<output>0.025</output>

<gadget id="calculator">20 / 0.025</gadget>
<output>800</output>

<result>800</result>