Order of Operations with and without variables

The variable z is directly proportional to x, and inversely proportional to y. when x is 4 and y is 13, z has the value 1.2307692307692. what is the value of z when x= 9, and y= 20

Arecipe calls for 32 fluid ounces of heavy cream.how many 1 pint containers of heavy cream are needed to make the recipe?

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.