Let a and B Be Sets with Cardinal Numbers, N(A)= $\text { If } B \subseteq A , n ( B ) = n ( A ) - n ( A - B )$

True/False

Let A and B be sets with cardinal numbers, n(A)= a and n(B)= b, respectively. Decide whether the statement is true or false.
- $\text { If } B \subseteq A , n ( B ) = n ( A ) - n ( A - B )$