The average (arithmetic mean) of four numbers is 7x + 5. If one of the numbers is x, what is the average of the other three numbers?	Choose the correct choice from the following choices:
A) x + 1
B) 3x + 3
C) 9x + 20/3
D) 5x + 4
E) 15x + 12
If the average of four numbers is 7x + 5, then the sum of all four numbers if 4 * (7x + 5) = 28x + 20. If one of the numbers is x, then the average of the remaining three numbers would be: (28x + 20 - x)/3 = (27x + 20)/3 = 9x + 20/3.   Answer is 9x + 20/3.
<result>C</result>
The average (arithmetic mean) of four numbers is 7x + 5. If one of the numbers is x, what is the average of the other three numbers?