$a)$ $\frac{3}{4}+\frac{3}{4}=\frac{6}{4}=1\frac{2}{4}=1\frac{1}{2}$

$\frac{2}{3}+\frac{1}{3}=\frac{3}{3}=1$

 

$b)$ $1\frac{2}{5}+\frac{4}{5}=1\frac{6}{5}=2\frac{1}{5}$

$3\frac{5}{8}+\frac{7}{8}=3\frac{12}{8}=4\frac{4}{8}=4\frac{1}{2}$

 

$c)$   $2\frac{1}{3}+3\frac{1}{3}=5\frac{2}{3}$

$4\frac{2}{5}+3\frac{4}{5}=7\frac{6}{5}=8\frac{1}{5}$

 

$d)$   $1\frac{2}{3}+2\frac{2}{3}+2\frac{1}{3}=5\frac{5}{3}=6\frac{2}{3}$

$6\frac{2}{5}+3\frac{1}{5}+2\frac{4}{5}=11\frac{7}{5}=12\frac{2}{5}$