A store buys a batch of sneakers at a price of 65 yuan per pair. If it sells a pair of sneakers at 88 yuan each, when there are 15 pairs left, it will make a profit of 520 yuan in addition to recovering all costs. How many pairs are there in this batch of sneakers? ?
商店以每双65元的价格购进一批球鞋，如果以每双88元出售，当卖到还剩15双时，除了收回全部成本以外，还获利520元，问这批球鞋共有多少双？
<gadget id="calculator">88 * 15</gadget>
<output>1_320</output>

<gadget id="calculator">1_320 + 520</gadget>
<output>1_840</output>

<gadget id="calculator">88 - 65</gadget>
<output>23</output>

<gadget id="calculator">1_840 / 23</gadget>
<output>80</output>

<result>80</result>