Can you guys me on this one or like answer it

Answer the following for 896.31 cm= km 100cm = 1m 1000m = 1km a) 0.0089631 b) 0.0089631 c) 8.9631 d) 89.631

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 360, a standard deviation of 4, and a margin of error of 2.5%

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.