The following data sufficiency problems consist of a question and two statements, labeled (1) and (2), in which certain data are given. You have to decide whether the data given in the statements are sufficient for answering the question. Using the data given in the statements plus your knowledge of mathematics and everyday facts (such as the number of days in July or the meaning of counterclockwise), you must indicate whether.
What is the average (arithmetic mean) of x and y ？（）
(1) The average of x+3 and y+5 is 14.
(2) The average of x, y, and 16 is 12.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
参考答案：D
解析：
alone is sufficient; the statement could be restated to say that x+y+3+5=14×2, or x+y=20; therefore, the average of x and y is 10. (2) alone is sufficient; the statement could be restated as x+y+16=12×3, or x+y=20; therefore, the average of x and y is 10.