1.a) \(\begin{array}{l}
\frac{1}{8} + \frac{3}{8} = \frac{{1 + 3}}{8} = \frac{4}{8}\\
 = \frac{1}{2}
\end{array}\)

1.b) 

\(\begin{array}{l}
\frac{{ - 2}}{5}.\frac{5}{{17}} = \frac{{( - 2).5}}{{5.17}}\\
 = \frac{{ - 2}}{{17}}
\end{array}\)

2.a) 

\(\begin{array}{l}
A = \frac{{26}}{3}.\frac{{2017}}{{2018}} + \frac{{26}}{3}.\frac{1}{{2018}} - \frac{5}{3}\\
 = \frac{{26}}{3}.\left( {\frac{{2017}}{{2018}} + \frac{1}{{2018}}} \right) - \frac{5}{3}\\
 = \frac{{26}}{3}.1 - \frac{5}{3}\\
 = \frac{{21}}{3} = 7
\end{array}\)

2.b)

\(\begin{array}{l}
11\frac{3}{{13}} + \left( {2\frac{4}{7} - 5\frac{3}{{13}}} \right)\\
 = \left( {11\frac{3}{{13}} - 5\frac{3}{{13}}} \right) + 2\frac{4}{7}\\
 = 6 + 2\frac{4}{7}\\
 = 8\frac{4}{7}
\end{array}\)