Lazy Yangyang, Happy, and Boiling Yangyang went on a trip and took a total of 15 single photos, 18 double photos, and 7 triple photos. If there are several people in the photo, how many photos will be printed, and how many photos will be printed in total?
懒羊羊、喜洋洋、沸羊羊出去旅游，一共拍了15张单人照、18张双人照、7张三人照．如果照片上有几个人，就要洗印几张，一共要洗印多少张照片？
<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<gadget id="calculator">36 + 21 + 15</gadget>
<output>72</output>

<result>72</result>