If n(A ×B) =858 and n(B)=22, find n(A).
n(A) =
n(A) means NUMBER OF NUMBERS () in a set of A.
you said n(AxB) is 858, and n(B) is 22, so n(A) = n(AxB/B) = 858/22 = 39.
So n(A) = 39.
+23 
) in a set of A.
