Two sets $$A = \{ 3,5,7,9 \} , B = \{ 3,7 \}$$ For the sets above, when $A - B = \{ a , 9 \}$, what is the value of $a$? [2 points] (1) 1 (2) 2 (3) 3 (4) 4 (5) 5
Two sets
$$A = \{ 3,5,7,9 \} , B = \{ 3,7 \}$$
For the sets above, when $A - B = \{ a , 9 \}$, what is the value of $a$? [2 points]\\
(1) 1\\
(2) 2\\
(3) 3\\
(4) 4\\
(5) 5