let's firstly convert the mixed fractions to improper, and then divide.
[tex]\bf \stackrel{mixed}{3\frac{3}{7}}\implies \cfrac{3\cdot 7+3}{7}\implies \stackrel{improper}{\cfrac{24}{7}}\\\\[-0.35em]~\dotfill\\\\\cfrac{24}{7}\div \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[/tex]
