HELP im not smart- ill mark u as brainiest

Last one and the bottom answer choice is y=(x-4)^2+1 you guys!

Xy x xy if a and b are positive integers such that a*b=9 and b*a=72 what is the value of a/b

You make a necklace using blue, purple, and green beads in a ration of 1: 1: 2. you use the total of 168 beads. how many green beads in the necklace?