Question

7 pupil of average age 12 leaves a class of 25 pupils of average age 14years if 6 new pupils of average age 11years join the class, what's is the average age of the pupils in the class

Answer 1

Good grief!
Why is it too much to expect students to post a question
using proper English, with correct grammar and punctuation ?

From this gibberish ....

Total ages of original class = 25*14 or 350
Ages of students that leave = 7*12 = 84
Ages of students that join = 6*11 = 66

total of ages at end = 350 - 84 + 66 = 332
total number of students at end = 25 - 7 + 6 = 24

new average age = 332/24 = appr 13.8