Помогите пожалуйста.Надобно всё

1.
а) 15/15 - ( 1/6 + 3/8 ) = 11/24
1) 1/6 + 3/8 = 4/24 + 9/24 = 13/24
2) 15/15 - 13/24 = 1 - 13/24 = 24/24 - 13/24 = 11/24
ответ: 11/24

b) ( 25/28 - 5/14 ) - ( 5/7 - 1/4 ) - 1/28 = 1/28
1) 25/28 - 5/14 = 25/28 - 10/28 = 15/28
2) 5/7 - 1/4 = 20/28 - 7/28 = 13/28
3) 15/28 - 13/28 = 2/28 = 1/14
4) 2/28 - 1/28 = 1/28
ответ: 1/28

с) 16/21 - ( 1/6 + 2/7 ) = 13/42
1) 1/6 + 2/7 = 7/42 + 12/42 = 19/42
2) 16/21 - 19/42 = 32/42 - 19/42 = 13/42
ответ: 13/42

d) ( 35/36 - 5/8 ) - ( 17/18 - 7/9) - 5/72 =
1) 35/36 - 5/8 = 70/72 - 45/72 = 25/72
2) 17/18 - 7/9 = 17/18 - 14/18 = 3/18 = 1/6
3) 25/72 - 1/6 = 25/72 - 12/72 = 13/72
4) 13/72 - 5/72 = 8/72 = 1/9
ответ: 1/9

5.
а) 3/4 - ( х + 1/20 ) = 1/5
3/4 - х - 1/20 = 1/5
7/10 - х = 1/5
-х = 1/5 - 7/10
-х = -1/2
х = 1/2
ответ: х = 1/2

b) 3/7х + 5/20х + 1/3х = 1/5
3/7х + 1/4х + 1/3х = 1/5
180х + 105х + 140х = 84
425х = 84
х= 84/425
ответ: х = 84/425

с) 2/3 - ( х - 1/20 ) = 2/7
2/3 - х + 1/20 = 2/7
43/60 - х = 2/7
-х = 2/7 - 43/60
-х = -181/420
х = 181/420
ответ: х = 181/420

d) 3/5х + 3/20х + 1/4х = 2/7
84х + 21х + 35х = 40
140х = 40
х = 40/140
х = 2/7
ответ: х = 2/7