For every X, the action [X] is defined: [X] is the greatest integer less than or equal to X. What is the value of [6.5] x [2/3] + [2] x 7.2 + [8.4] - 6.6? Choose one:
A) 12.6.
B) 14.4.
C) 15.8.
D) 16.2.
E) 16.4
[6.5] x [2/3] + [2] x 7.2 + [8.4] - 6.6   = 6*0 + 2*7.2 + 8 - 6.6   = 0 +14.4 +1.4   15.8   Answer 15.8.
<result>C</result>
For every X, the action [X] is defined: [X] is the greatest integer less than or equal to X. What is the value of [6.5] x [2/3] + [2] x 7.2 + [8.4] - 6.6?