brand of table tennis rackets launched a promotional plan for a racket after the Beijing Olympic Games: the racket is priced at RMB 60 each, and the buyer can get a lottery coupon, and the accumulation of 3 lottery coupons can be exchanged for a racket. It can be seen from this, how much is the value of a lottery ticket.
某品牌乒乓球拍在北京奥运会后推出一款球拍的促销计划：该球拍每只售价为人民币60元，同时购买者可获赠1张奖券，积累3张奖券可兑换1只球拍．由此可见，1张奖券价值为多少元．
<gadget id="calculator">60 * 3</gadget>
<output>180</output>

<gadget id="calculator">180 / 4</gadget>
<output>45</output>

<gadget id="calculator">60 - 45</gadget>
<output>15</output>

<result>15</result>