The store buys a batch of footballs at a price of 100 yuan each, and sells them for 130 yuan each. When the remaining 20% is sold, the profit is 960 yuan after deducting the cost. Find the number of this batch of footballs.
商店以每个100元的价格购送一批足球，售价为130元每个，卖到剩下20%时，除去成本，还获利960元，求这批足球的个数．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">130 * (1/5)</gadget>
<output>26</output>

<gadget id="calculator">130 - 26 - 100</gadget>
<output>4</output>

<gadget id="calculator">960 / 4</gadget>
<output>240</output>

<result>240</result>