Let's use the variable 'n' to represent the cost of a notebook and 'p' the cost of a pen.
If Kennel wants an equal number of notebooks and pens, we can create a group of one notebook and one pen, and the resulting cost will be 'n + p'
Then, to find the number of these groups Kennel can buy, we just need to divide the amount of money ($40) by the cost of the group of one notebook and one pen:
If the result is not a whole number, we need to round it down, since we can't spend more money than the budget of $40.