12. Cat and Mouse. If $n$ cats eat $n$ mice in $n$ hours, then how many mice will $p$ cats eat in $p$ hours?
12.Let's assume that cats eat mice, not the other way around. If $n$ cats eat $n$ mice in $n$ hours, then one cat will eat 1 mouse in $n$ hours, and in 1 hour - $\frac{1}{n}$ of a mouse. Consequently, $p$ cats will eat $\frac{p^{2}}{n}$ mice in $p$ hours.