One can determine the consumers’ surplus if the are known tax paid maximum buying price price paid maximum buying price and price paid maximum buying price and tax paid

The answer to this question is:  Maximum buying price and Price paid
Maximum buying price refers to the largest amont that consumers are willing to pay to obtain a certain product.
Price refers to the total resource that the consumers have spent to obtain a certain product. Comparing this two factors will result in the amount that indicates the consumer's surplus

Earn positive economic profit in the long run if it can maintain barriers to entry, assuming no changes in costs or market demand