數學問題?

1. 7[5(x-3)+12]=5[7-4(x+5)]
35x-105+12=35-20x-100
55x=28
x=28/55

2. x-(x-1/2)=2-(x+2/3)
x-x+1/2=2-x+2/3
1/2=8/3-x
x=13/6

3. k/3+(3k+4/9)=2-3k/12
43k/12=14/9
k=56/129

4. y/4-5(3-y)/3=2y-17/6
y/4-5+5y/3=2y-17/6
47/6=y/12
y=94

5. 3x-2/5-13/25=8(3-x)/3
3x-23/25=8-8x/3
17x/3=223/25
x=669/425

6.3/8(x-3)+7/5=5x/6+0.7x
3x/8-9/8+7/5=5x/6+7x/10
11/40=139x/120
x=33/139