In the days of Sichuan Wenchuan Earthquake Relief in 2008. Uncle Li of the People's Liberation Army fought for 60 hours on the front line in the first 4 days, and he fought on the front line for an average of 15 hours a day in the next 3 days. How many hours does Uncle Li work on average every day?
在2008年四川汶川抗震救灾的日子里．解放军李叔叔前4天在一线共奋战60小时，后3天平均每天在一线奋战15小时．李叔叔平均每天工作多少小时？
<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<gadget id="calculator">60 + 45</gadget>
<output>105</output>

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

<gadget id="calculator">105 / 7</gadget>
<output>15</output>

<result>15</result>