Please help i’m so lost lol

How many sides does a regular polygon have if each exterior angle measures 72a.3b.4c.5d.6

What are the exclude value of mn+3m

Abicycle training wheel has a radius of 3 inches. the bicycle wheel has a radius of 10 inches.approximately how much smaller, in square inches and rounded to the nearest hundredth, is the area of the training wheel than the area of the regular wheel? *