Why is it difficult to determine the value of certain goods and services?

Public goods often suffer free-riders' problem. Although each user values them, none has an incentive to pay to maintain them. Hence, the valuation such goods and services may help the resource managers to deal with the effects of market failures, by measuring their social and opportunity costs.

Explanation:

Economic value is a measure of the benefit provided by a good or service to an economic agent. ... If a consumer is willing to buy a good, it implies that the customer places a higher value on the good than the market price.

Explanation:

answerpounds of plastic to purchase 200+60-20=(240);

answer the law of increasing costs;