If the average (arithmetic mean) of the four numbers K, 2K + 3, 4K – 4 and 5K + 1 is 63, what is the value of K?  Choose the correct choice from the following answers:
A) 11
B) 15 3/4
C) 21
D) 23
E) 25 3/10
K + 2K +3 + 4K - 4 + 5K +1 = 12K   (12K)/4 = 63   12K = 63 * 4= 
<gadget id="calculator">63 * 4</gadget>
<output>252</output>
252   K= 252 / 12= 
<gadget id="calculator">252 / 12</gadget>
<output>21</output>
21   Answer 21.
<result>C</result>
If the average (arithmetic mean) of the four numbers K, 2K + 3, 4K – 4 and 5K + 1 is 63, what is the value of K?