Let x, y, and z be non-zero numbers such that the average (arithmetic mean) of x and twice y is equal to the average (arithmetic mean) of y and twice z. What is the average (arithmetic mean) of x and y?
A.z2
B.z
C.2z
D.z − x
E.z − y
我的答案:
Let x, y, and z be non-zero numbers such that the average (arithmetic mean) of x and twice y is equal to the average (arithmetic mean) of y and twice z. What is the average (arithmetic mean) of x and y?