GWD管卫东GMAT 第7套题 数学第21题 求讲解 谢谢 正确答案是E 我觉得C……

GWD管卫东GMAT 第7套题 数学第21题 求讲解 谢谢 正确答案是E 我觉得C……
Q21:
Theater M has 25 rows with 27 seats in each row.How many of the seats were occupied during a certain show?
(1) During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows.
(2) During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows.

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.