单选题The average (arithmetic mean) of c and d is 12, and the average of c, d, and e is 10. What is the value of e?A 6B 10C 12D 18E 20
题目
单选题
The average (arithmetic mean) of c and d is 12, and the average of c, d, and e is 10. What is the value of e?
A
6
B
10
C
12
D
18
E
20