x + 1$$\frac{9}{12}$$ = 2$$\frac{5}{12}$$
x + $$\frac{21}{12}$$ = $$\frac{29}{12}$$
x = $$\frac{29}{12}$$ - $$\frac{21}{12}$$
x = $$\frac{8}{12}$$ = $$\frac{2}{3}$$
Ответ: $$\frac{2}{3}$$