Suppose a = {2, 5, 7, 9, 13, 25, 26}. (a) find n(a). (b) true or false: 13 ∈ a (c) true or false: 26 ∉ a (d) true or false: 10 ∉ a

n(A) is the number of elements is A, sometimes written |A|.  I count 7.  n(A)=7

13 is among the elements of A, so 13 ∈ A  is TRUE

26 is among the elements of A, so 26 ∉ A   is FALSE

10 isn't in A, so 10 ∉ A  is TRUE

b.-4 units

all you   do is count how many times you move