[tex]\begin{array}{ccll} \stackrel{cups}{flour}&pizzas\\ \cline{1-2} 39&6\\ x&4 \end{array}\implies \cfrac{39}{x}=\cfrac{6}{4}\implies \cfrac{39}{x}=\cfrac{3}{2}\implies 78=3x\implies \boxed{26=x} \\\\[-0.35em] ~\dotfill\\\\ \begin{array}{ccll} \stackrel{cups}{flour}&pizzas\\ \cline{1-2} 39&6\\ 13&y \end{array}\implies \cfrac{39}{13}=\cfrac{6}{y}\implies 3=\cfrac{6}{y}\implies 3y=6\implies \boxed{y=2}[/tex]