Выполним вычисления по действиям:
1) $$5\frac{4}{5} = \frac{5 \cdot 5 + 4}{5} = \frac{29}{5}$$.
2) $$\frac{29}{4} : \frac{29}{5} = \frac{29}{4} \cdot \frac{5}{29} = \frac{5}{4}$$.
3) $$3 - \frac{19}{30} = \frac{3 \cdot 30 - 19}{30} = \frac{90 - 19}{30} = \frac{71}{30}$$.
4) $$\frac{3}{4} \cdot \frac{71}{30} = \frac{1}{4} \cdot \frac{71}{10} = \frac{71}{40}$$.
5) $$\frac{5}{4} - \frac{71}{40} = \frac{5 \cdot 10 - 71}{40} = \frac{50 - 71}{40} = \frac{-21}{40} = -0.525$$.
Ответ: -0,525