Given height and width of bookshelf is
[tex]x^2-6x-7[/tex]and
[tex]x^2+3x+2[/tex]respectively.
So we can write height of bookshelf as:
[tex]x^2-6x-7=(x+1)(x-7)[/tex]and width =
[tex]x^2+3x+2=(x+1)(x+2)[/tex]Now, height of cubbies is x+2 and width is x-7.
So, if we have n cubbies, height of each cubbies would be
[tex]=\frac{x+2}{n}[/tex]This is the required answer.