A+(-0,6+7/12) при a=1/15, 6,4+(-3.3/6+a) при a=4/15?

Решите задачу:

$a+(-0,6+ \frac{7}{12}) \\ 1)-0,6+ \frac{7}{12}=- \frac{3}{5}+ \frac{7}{12}= \frac{-36+35}{60}=- \frac{1}{60} \\ 2)a- \frac{1}{60}= \frac{1}{15}- \frac{1}{60}= \frac{4-1}{60}= \frac{3}{60}= \frac{1}{20}=0,05 \\ \\ 6,4+(-3 \frac{3}{6}+a)=6,4-3 \frac{3}{6}+a \\ 1)6,4-3 \frac{3}{6}= \frac{64}{10}- \frac{21}{6}= \frac{192-105}{30}= \frac{87}{30}= \frac{29}{10} \\ 2) \frac{29}{10}+a= \frac{29}{10}+ \frac{4}{15}= \frac{87+8}{30}= \frac{95}{30}= \frac{19}{6}=3 \frac{1}{6}$