數學問題(P.S.連詳細步驟Thanks)

1)
[(2x - 1) / 2] - [(x + 1) / 3] = 1/2
[3(2x - 1) / 6] - [2(x + 1) / 6] = 3/6
3(2x - 1) - 2(x + 1) = 3
6x - 3 - 2x - 2 = 3
4x = 8
x = 2


*****
2)
p / 6 = (7 / 2) - p
p / 6 = (21 / 6) - (6p / 6)
p = 21 - 6p
7p = 21
p = 3


*****
3)
( x + 3 ) / 2 0 = ( 2 1 - x ) / 2 8
( x + 3 ) / 5 = ( 2 1 - x ) / 7
7(x + 3) = 5(21 - x)
7x + 21 = 105 - 5x
12x = 84
x = 7


*****
4)
[( 3 - 2y ) / 4] + (5 / 1 2) = [( y - 3 ) / 2] - (1 / 3)
[3( 3 - 2y ) / 12] + (5 / 1 2) = [6( y - 3 ) / 12] - (4 / 12)
3( 3 - 2y ) + 5 = 6( y - 3 ) - 4
9 - 6y + 5 = 6y - 18 - 4
12y = 36
y = 3

1.
( 2 x - 1 ) / 2 - ( x + 1 ) / 3 = 1 / 2
6x-3-2x-2=3
4x=8
x=2

2)
p / 6 = 7 / 2 - p
p=21-6p
7p=21
p=3

3)
( x + 3 ) / 2 0 = ( 2 1 - x ) / 2 8
1.4x+4.2=21-x
0.4x=16.8
x=42

4)
( 3 - 2 y ) / 4 + 5 / 1 2 = ( y - 3 ) / 2 - 1 / 3
9-6y+20=6y-12-4
-6y+29=6y-16
-12y=-45
y=3.75