$\bf \stackrel{mixed}{3(3)/(7)}\implies \cfrac{3\cdot 7+3}{7}\implies \stackrel{improper}{\cfrac{24}{7}}\\\\[-0.35em]~\dotfill\\\\\cfrac{24}{7}/ \cfrac{6}{7}\implies \cfrac{24}{7}\cdot \cfrac{7}{6}\implies \cfrac{24}{6}\cdot \cfrac{7}{7}\implies 4\cdot 1\implies 4$