[tex]\large\boxed{\begin{array}{l}\rm p\longrightarrow prec_{\!\!,}o\,do\,pastel\\\rm c\longrightarrow prec_{\!\!,}o\,do\,caldo\\\begin{cases}\sf 4p+2c=20\div2\\\sf 3p+3c=18\div(-3)\end{cases}\\\\+\underline{\begin{cases}\sf2p+\backslash\!\!\!c=10\\\sf-p-\backslash\!\!\!c=-6\end{cases}}\\\sf p=4\\\sf 2p+c=10\longrightarrow prec_{\!\!,}o\,de\,dois\,past\acute eis\,e\,um\,caldo.\end{array}}[/tex]
