1. Выполним действия по порядку:
$$3\frac{6}{25}-(7-6\frac{8}{25})+1\frac{17}{25}=4$$
1) $$7-6\frac{8}{25}=6\frac{25}{25}-6\frac{8}{25}=\frac{25-8}{25}=\frac{17}{25}$$
2) $$3\frac{6}{25}-\frac{17}{25}=3\frac{6}{25}-\frac{17}{25}=2\frac{31}{25}-\frac{17}{25}=2\frac{31-17}{25}=2\frac{14}{25}$$
3) $$2\frac{14}{25}+1\frac{17}{25}=3\frac{14+17}{25}=3\frac{31}{25}=3+1\frac{6}{25}=4\frac{6}{25}$$
Ответ: $$4\frac{6}{25}$$