и) 1$$\frac{5}{12}$$ - $$\frac{9}{10}$$ = 1$$\frac{25}{60}$$ - $$\frac{54}{60}$$ = $$\frac{85}{60}$$ - $$\frac{54}{60}$$ = $$\frac{31}{60}$$
Ответ: $$\frac{31}{60}$$