The average age of an adult class is 40 years. 12 new students with an avg age of 34years join the class. Therefore decreasing the average by 4 years. Find what was the original average age of the class?  Choose the correct answer:
A) 6 B) 12 C) 16 D) 20 E) 22

Rationale: "let original strength = y then , 40 y + 12 x 34 = ( y + 12 ) x 36 â ‡ ’ 40 y + 408 = 36 y + 432 â ‡ ’ 4 y = 48 â ˆ ´ y = 6 a"
Answer: A