A table tennis racket is 15 yuan. If you buy 2 pairs of such table tennis rackets, how much is the total cost?
一只乒乓球拍15元，如果买2副这样的乒乓球拍，一共需要多少元．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<result>60</result>