Simplify the number using the imagery unit 1

Solve for x i'll try to attach the files bc it's not letting me for some reason

You have a 32-foot fence around a square garden. there are 4 equal sections. you paint 13 of one section of the fence. what fraction of the fence did you paint? you have a 32-foot fence around a square garden. there are 4 equal sections. you paint 13 of one section of the fence. what fraction of the fence did you paint?

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)