The teacher is 45 years old this year. He has three students. Xiao Ming is 15 years old, Xiao Hong is 11 years old, and Xiao Liang is 7 years old.
老师今年45岁，他有三个学生，小明今年15岁，小红今年11岁，小亮今年7岁，要过多少年，老师的岁数等于他们三个学生岁数的和．
<gadget id="calculator">45 - 15 - 11 - 7</gadget>
<output>12</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<result>6</result>