Ma how did you get that 21 in n(B)
2 answers
The answer to this question depends on the context of the question. If the question is asking how I got 21 in a specific equation, then I would need to provide the equation and the steps I took to solve it. If the question is asking how I got 21 in a general sense, then I would need to provide more information about the context of the question.
I mean the second step of that n(B)