\[\begin{array}{l}
C1:\\
\left( {\frac{2}{3} + \frac{3}{4}} \right) \times \frac{1}{2}\\
= \left( {\frac{8}{{12}} + \frac{9}{{12}}} \right) \times \frac{1}{2}\\
= \frac{{17}}{{12}} \times \frac{1}{2}\\
= \frac{{17}}{{24}}\\
\left( {\frac{1}{3} + \frac{1}{2}} \right) \times \frac{2}{5}\\
= \left( {\frac{2}{6} + \frac{3}{6}} \right) \times \frac{2}{5}\\
= \frac{5}{6} \times \frac{2}{5}\\
= \frac{1}{3}\\
C2:\\
\left( {\frac{2}{3} + \frac{3}{4}} \right) \times \frac{1}{2}\\
= \frac{2}{3} \times \frac{1}{2} + \frac{3}{4} \times \frac{1}{2}\\
= \frac{1}{3} + \frac{3}{8}\\
= \frac{8}{{24}} + \frac{9}{{24}}\\
= \frac{{17}}{{24}}\\
\left( {\frac{1}{3} + \frac{1}{2}} \right) \times \frac{2}{5}\\
= \frac{1}{3} \times \frac{2}{5} + \frac{1}{2} \times \frac{2}{5}\\
= \frac{2}{{15}} + \frac{1}{5}\\
= \frac{2}{{15}} + \frac{3}{{15}}\\
= \frac{5}{{15}}\\
= \frac{1}{3}
\end{array}\]