a) $$4\frac{3}{5}n+m$$ при $$n=1\frac{4}{23}$$, $$m=6\frac{13}{30}$$;
$$4\frac{3}{5}\cdot 1\frac{4}{23}+6\frac{13}{30}=\frac{4\cdot 5+3}{5}\cdot \frac{1\cdot 23+4}{23}+6\frac{13}{30}=\frac{23}{5}\cdot \frac{27}{23}+6\frac{13}{30}=\frac{27}{5}+6\frac{13}{30}=5\frac{2}{5}+6\frac{13}{30}=5\frac{12}{30}+6\frac{13}{30}=11\frac{25}{30}=11\frac{5}{6}$$.
Ответ: $$11\frac{5}{6}$$