Xiaodong used her membership card to buy books, and she bought a set of "Up and Down Five Thousand Years", 4 copies in each set, and each copy was 39.6 yuan. It only cost 142.58 yuan, how much money can she save by using the membership card?
小东用会员卡买书，她买了一套《上下五千年》，每套4本，每本39.6元．只花了142.58元，她使用会员卡能节约多少钱？
<gadget id="calculator">39.6 * 4</gadget>
<output>158.4</output>

<gadget id="calculator">158.4 - 142.58</gadget>
<output>15.82</output>

<result>15.82</result>