In a coconut grove, (x + 2) trees yield 30 nuts per year, x trees yield 120 nuts per year and (x – 2) trees yield 180 nuts per year. If the average yield per year per tree be 100, find x. Choose the correct option:
A) 3 B) 4 C) 5 D) 6 E) 10

Rationale: "( x + 2 ) × 30 + x × 120 + ( x − 2 ) × 180 / ( x + 2 ) + x + ( x − 2 ) = 100 ⇒ 330 x − 300 / 3 x = 100 ⇒ 30 x = 300 ⇒ x = 10 answer e"
Answer: E