$a)2\frac{5}{6}+3\frac{2}{3}+1\frac{5}{12}=2\frac{10}{12}+3\frac{8}{12}+1\frac{5}{12}=6\frac{23}{12}=7\frac{11}{12}$

$b)2,4+0,05+14,9=2,45+14,9=2,45+14+0,9=16,45+0,9=17,35$ $b)2,4+0,05+14,9=2,45+14,9=2,45+14+0,9=16,45+0,9=17,35$

$c)1,5+2\frac{1}{3}+3\frac{1}{5}=1\frac{1}{2}+2\frac{1}{3}+3\frac{1}{5}=1\frac{15}{30}+2\frac{10}{30}+3\frac{6}{30}=6\frac{31}{30}=7\frac{1}{30}$

$d)14\frac{7}{12}-\frac{3}{4}-1\frac{5}{6}=13\frac{19}{12}-\frac{9}{12}-1\frac{10}{12}=13\frac{10}{12}-1\frac{10}{12}=12$

$e)40-0,8-0,32=39,2-0,32=39,2-0,2-0,12=39-0,12=38,88$

$f)18,2-1\frac{1}{4}-2\frac{1}{5}=18,2-1,25-2,2=18,2-2,2-1,25=16-1,25=14,75$