9% of 40 is what number?

Li buys supplies so he can make and sell key chains. he begins to make a profit only after he sells 4 key chains. what point on the graph makes the most sense in this situation?

Aye asap pls ! markin da brainiest too ! btw da step choices are all add, distribute, divide, n subtract

Why is it so easy to buy on impulse and overspend with a credit card? what could you do to counteract this tendency?