The answer is A,because the way your question is written,there would be 4 molecules of salt (NA) and one molecule of CL (Chlorine)
Eleven subtract nine is two; eight adding three is eleven (2,11)
You are suppose to subtract making it
X+7=13
-7=-7
______
X=6
Cos38 = 7,8/x
X= 7,8/cos38
= 9,90
