How many even integers n, such that 20<=n<=240 are of the form 3k+4, where k is any natural number?  Choices.
A) 31  B) 33  C) 35  D) 37  E) 39

Rationale: "the first number is 22 = 16 + 6 ( 1 ) . we can continue adding 6 to make a list : 22 , 28 , 34 , . . . the last number is 238 = 16 + 6 ( 37 ) there are 37 numbers in the list . the answer is d ."
Answer: D