1/3 is the answer I believe
Answer:
The number of baseball card to begin with is 143
Step-by-step explanation:
Let The number of baseball cards = x
The number of sold baseball card = 60% of x
= 0.6 x
The number of left baseball card = x - 0.6 x = 0.4 x
The number of card gave away = 30 % of left cards
= 0.3 × 0.4 x = 0.12 x
The number of card left in his possession = 40
So, 0.6 x + 0.12 x + 40 = x
Or, 40 = x - 0.6 x - 0.12 x
Or, 40 = 0.28 x
∴ x =
= 142.85 ≈ 143
Hence The number of baseball card to begin with is 143 Answer
An exponent is a number written above and to the right side of a value or number in math. The value or number is called the base, and the expression is read out as;
"Base raised to the power of exponent."
An example is given below;

In this example, 10 is the base and 3 is the EXPONENT.
The expression is now read out as,
"10 raised to the power of 3"
Note that even unknown values (such x as we commonly use in math) can also be an exponent or base. For example, we can have;

So basically, an exponent indicates the number of times a number is used to multiply itself.
I think it's A but I'm not 100% sure