In a school of $240$ pupils, $\frac{3}{5}$ have lunch at school. Of those, $\frac{1}{4}$ bring their own lunch. How many pupils bring their own lunch?

Numa escola com $240$ alunos, $\frac{3}{5}$ almoçam na escola. Desses, $\frac{1}{4}$ trazem o almoço de casa. Quantos alunos trazem o almoço de casa?