Teacher Zhang was busy with work and did not go home for 5 days. After returning home, he tore off the calendar for these 5 days. The sum of the numbers of these 5 days was 45. Ask: What is the day when Teacher Zhang returns home?
张老师因工作忙，5天没有回家，回家后一次撕下这5天的日历，这5天的日期的数字相加的和是45，问：张老师回家这天是多少号．
<gadget id="calculator">45 / 5</gadget>
<output>9</output>

<gadget id="calculator">9 + 2</gadget>
<output>11</output>

<result>11</result>