Respuesta :

[tex]\begin{array}{ccc}30\ students&-&9\ pizzas\\\\40\ students&-&x\ pizzas\end{array}\ \ \ \ |cross\ multiply\\\\\\30\cdot x=40\cdot9\\30x=360\ \ \ \ \ |divide\ both\ sides\ by\ 30\\\boxed{x=12}\leftarrow answer[/tex]
AhmetÖzkan1907
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