11s-9 is the answer to ur question
So the number of pencils bought can be represented by an equation:

, where n is the number of notebooks bought. Since Helen bought 5 notebooks, simply plug 5 into n:

. So Helen bought 12 pencils.
A square area=legnth times width
but for a square, legnth=width so
area=legnth^2
are=49
49=legnth^2
square root of both sides
7=legnth
the answer is 7