The Cultural Palace Cinema is showing a new movie, and each ticket costs 20 yuan. Ding Ding and his parents took the discount card to buy tickets, each ticket was 15% off, how much did it cost to buy three tickets?
文化宫电影院正在播放一部新电影，每张票价20元．丁丁和父母拿着优惠卡去买票，每张票打八五折，买三张票共花了多少钱？
<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">20 * (17/20) * 3</gadget>
<output>51</output>

<result>51</result>