The arithmetic mean of 3a + 4 and another number is 2a. What is the average of the other number and a?

A 2a

B a-4

C a-2

D a + 2

Correct Answer: Option C

suppose, another number is x here, 3a+4+x/2 = 2a or, 3a+4+x=4a or, x=a-4 average of , a-4+a/2 = a-2