The perimeter off a regular octagon is p and the length of a side is s. The formula of s is: s=p divided by 8

a)Find the length of a side when the perimeter is 104cm

b)write down a formular for the perimeter of a regular triangle. P=?

c)find p when one side of the triangle is 4cm?

I know these are really hard so if u could just help with as many as you can that would be great thanks !!!!!