Resposta :
[tex]\Large\boxed{\begin{array}{l}\begin{array}{cc}\sf refrigerantes &\sf horas\\\sf 3000&\sf6\\\sf 4000&\sf x\end{array}\\\\\sf x=\dfrac{4000\cdot6}{3000}\\\\\sf x=\dfrac{24000}{3000}\\\\\sf x=8\, horas~\checkmark\end{array}}[/tex]
[tex]\Large\boxed{\begin{array}{l}\begin{array}{cc}\sf refrigerantes &\sf horas\\\sf 3000&\sf6\\\sf 4000&\sf x\end{array}\\\\\sf x=\dfrac{4000\cdot6}{3000}\\\\\sf x=\dfrac{24000}{3000}\\\\\sf x=8\, horas~\checkmark\end{array}}[/tex]