In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.

In economics , utility is the satisfaction or benefit derived by consuming a product ; thus the marginal utility of a goods or service is the change in the utility from an increase in the consumption of that good or service .
Marginal utility is a concept from economics that describes the change in utility from consuming more or less of a good or service .

Saint-Denis ( -RSB- , or unofficially Saint-Denis de la Re ́ union for disambiguation ) is the " pre ́ fecture " ( administrative capital ) of the French overseas region and department of Re ́ union , in the Indian Ocean .
Saint-Denis is the administrative capital ( " pre ́ fecture " ) of the French controlled island of Re ́ union , in the Indian Ocean .

An emergency telephone is a phone specifically provided for making calls to emergency services and is most often found in a place of special danger or where it is likely that there will be a need to make emergency calls .

An emergency telephone is a special telephone that can be used in an emergency situation .