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 ❣️
