What is the perimeter of AYXZ?

Geometry ? i don't know how to do any of these.

Apublic library wants to place 4 magazines and 9 books on each display shelf. the expressions 4s +9s represents the total number of items that will be displayed on s shelves. simplify this expression

Divide. –4.2 ÷ 6 = a –0.7 b 0.7 c –7 d 7 me