How do you create a model for 0.33 divided by 3

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

Some boys and girls were asked if they had a pet. one third of the group were boys. there were 20 boys. 20% of the girls had a pet. boys with a pet : girls with a pet = 1 : 5 i need to know how many girls there are.

    choose the correct definition for  extremo.  a.  end      b.  extra      c.  extract      d.  eventual