The average (arithmetic mean) of four numbers is 5x + 3. If one of the numbers is 2x, what is the average of the other three numbers? Pick one.
A) x + 1
B) 3x + 3
C) 4x + 1
D) 5x + 3
E) 6x + 4
The sum of all four numbers is 4 * (5x + 3) = 20x + 12.   If one of the numbers is 2x, the sum of the other 3 numbers is 18x+12.   The average of the remaining three numbers is (18x+12)/3 = 6x+4.   The answer is 6x + 4.
<result>E</result>
The average (arithmetic mean) of four numbers is 5x + 3. If one of the numbers is 2x, what is the average of the other three numbers?