In a competitive market, how does a consumer determine the optimal quantity of a good to purchase based on marginal benefit and market equilibrium?

In a competitive market, a consumer decides how much of a good to buy by comparing the marginal benefit to the price of the good. Marginal benefit is the extra satisfaction or value a consumer gets from consuming one more unit of a product. When the price of the good is equal to the marginal benefit, the consumer is at market equilibrium, meaning they are making the best choice for their money. For example, if a consumer finds that buying one more slice of pizza gives them a satisfaction of $3 and the price of the slice is also $3, they will buy that slice because the benefit matches the cost. If the marginal benefit is less than the price, they would choose not to buy that extra slice, as it wouldn’t be worth it.