During the earthquake relief work in Sichuan, Uncle Liu, a special police officer, fought for 74 hours in Wenchuan County in the first 4 days, and worked 15 hours a day in Shifang City for the next 3 days. How many hours does Uncle Liu work on average this week?
在四川抗震救灾的日子里，特警刘叔叔前4天在汶川县共奋战74小时，后3天在什邡市每天工作15小时．这一周刘叔叔平均每天工作多少小时？
<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<gadget id="calculator">45 + 74</gadget>
<output>119</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<gadget id="calculator">119 / 7</gadget>
<output>17</output>

<result>17</result>