Respuesta :

[tex]\bf \begin{array}{ccll} \stackrel{dog~food}{cans}&days\\ \cline{1-2} 40&31\\ x&6 \end{array}\implies \cfrac{40}{x}=\cfrac{31}{6}\implies \cfrac{40\cdot 6}{31}=x\implies \cfrac{240}{31}\implies 7\frac{23}{31}=x[/tex]