Explain why you need to know the exchange rate when you travel to a foreign country

The amount of tears in the room (denoted by ttt) can be defined as a function of the number of people present in the room (denoted by ppp), the number of chopped onions in the room (denoted by ooo), and the deliciousness of the onions (denoted by ddd) using this formula: t =3\cdot \dfrac{p\cdot o^3}{d^2}t=3? d 2 p? o 3 ?