Answers

1. Answer:

   Teacher’s age is 32.

   Step-by-step explanation:
   
   How you count the average age for people is:
   (age of person 1 + age of person 2 … ) / number of people = average age
   

   Let’s start by observing that we’ve got 2 equations coming from the text:

   • average of just students
     20 students x 11 (average for a student) = sum of age of students
     20 x 11 = 220
   • average of student and teacher
     let’s say x is age of teacher
     together students & teacher is 20 + 1 = 21 people
     (20 students x 11 + x)/ (20 + 1) = 12
     (220 + x) / 21 = 12
     220 + x = 12 * 21
     x = 12 *21 – 220
     x = 252 – 220
     x = 32

   hope this helps ❣️

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