A store buys a batch of volleyballs for 55 yuan each, and sells them for 80 yuan each. When the remaining (1/4) is sold, not only the cost is recovered, but also a profit of 960 yuan. How many volleyballs should you buy?
某商店以每个55元购进一批排球，售价每个80元，当卖剩下(1/4)时，不仅收回了成本，还获利960元，求购进排球多少个？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">80 * (3/4)</gadget>
<output>60</output>

<gadget id="calculator">60 - 55</gadget>
<output>5</output>

<gadget id="calculator">960 / 5</gadget>
<output>192</output>

<result>192</result>