Is it possible to change $15 into an equal number of half-dollars, quarters and dimes?

Aresearch group wants to find the opinions’ of city residents on the construction of a new downtown parking garage. what is the population of the survey downtown shoppers downtown visitors downtown workers city residents

Asurvey of 45 teens found that they spent an average of 25.6 hours per week in front of a screen (television, computer, tablet, phone, based on the survey’s sample mean, which value could be the population mean? 2.3 hours 27.4 hours 75.3 hours 41.5 hours

What is the missing reason in the proof? segment addition congruent segments theorem transitive property of equality subtraction property of equality?