a) $$19\frac{1}{4} = \frac{19 \cdot 4 + 1}{4} = \frac{76 + 1}{4} = \frac{77}{4}$$.
б) $$6\frac{2}{7} = \frac{6 \cdot 7 + 2}{7} = \frac{42 + 2}{7} = \frac{44}{7}$$.
в) $$7\frac{1}{5} = \frac{7 \cdot 5 + 1}{5} = \frac{35 + 1}{5} = \frac{36}{5}$$.
г) $$3\frac{8}{13} = \frac{3 \cdot 13 + 8}{13} = \frac{39 + 8}{13} = \frac{47}{13}$$.
д) $$1\frac{8}{15} = \frac{1 \cdot 15 + 8}{15} = \frac{15 + 8}{15} = \frac{23}{15}$$.
Ответ: а) $$\frac{77}{4}$$; б) $$\frac{44}{7}$$; в) $$\frac{36}{5}$$; г) $$\frac{47}{13}$$; д) $$\frac{23}{15}$$