$(1\frac{2}{3} - \frac{1}{2}) \div (\frac{7}{12} \times 2)=(\frac{5}{3}-\frac{1}{2})\div(\frac{7}{6})=(\frac{10-3}{6})\times \frac{6}{7}=\frac{7}{6}\times \frac{6}{7}=1=\frac{49}{49}$