1) 9:(x +5)=3
x +5 =9:3
x =3-5
x= -2
проверка
9:(-2+5)=3
9:3=3
3=3
2) ((7x+1):4)+2=11
(7x+1):4=11-2
7x = 9 × 4
7x = 36 -1
x = 35:7
x=5
3) 5: (x+3 )+ 2/3= 1
5 2
––––––– + ------ = 1
x+3 3
5
---------- = 1 - 2
x+3 --------
3
5. 1
--------------- =. -------
x +3. 3
15= x + 3
-x= 3-15
-x = -12
x=12