The sum of the ages of the four classmates and the teacher is 80 years old. Two years later, the sum of the ages of these four students is exactly equal to the age of the teacher. How old is the teacher?
四个同学与老师的年龄和是80岁．2年以后，这四个同学的年龄和正好等于老师的年龄．老师今年多少岁．
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">80 + 10</gadget>
<output>90</output>

<gadget id="calculator">90 / 2</gadget>
<output>45</output>

<gadget id="calculator">45 - 2</gadget>
<output>43</output>

<result>43</result>