A football is sewn from 12 pieces of black leather (pentagonal) and 20 pieces of white leather (hexagonal). There are 180 pieces of white skins, at least how many pieces of black skins are needed to use up the white skins?
一个足球由12块黑皮(五边形的)和20块白皮(六边形的)缝制而成．现有180块白皮，至少要配多少块黑皮才能把白皮用完？
<gadget id="calculator">12 / 20</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) * 180</gadget>
<output>108</output>

<result>108</result>