$a\text{)}\frac{3}{13}+\frac{5}{13}=\frac{3+5}{13}=\frac{8}{13}$    

$b\text{)}\frac{2}{15}+\frac{7}{15}=\frac{2+7}{15}=\frac{9}{15}=\frac{3}{5}$  

$c\text{)}\frac{9}{17}+\frac{12}{17}=\frac{9+12}{17}=\frac{21}{17}=1\frac{4}{17}$  

$d\text{)}\frac{5}{12}+\frac{11}{12}=\frac{5+11}{12}=\frac{16}{12}=\frac{4}{3}=1\frac{1}{3}$  

$e\text{)}2\frac{3}{8}+3\frac{3}{8}=5\frac{3+3}{8}=5\frac{6}{8}=5\frac{3}{4}$  

$f\text{)}1\frac{2}{9}+5\frac{4}{9}=6\frac{2+4}{9}=6\frac{6}{9}=6\frac{2}{3}$  

$g\text{)}4\frac{3}{5}+2\frac{4}{5}=6\frac{3+4}{5}=6\frac{7}{5}=7\frac{2}{5}$  

$h\text{)}3\frac{5}{8}+2\frac{7}{8}=5\frac{5+7}{8}=5\frac{12}{8}=6\frac{4}{8}=6\frac{1}{2}$