1. 2
2. 7
3. 16
4. 6
5. b
6. -b
方程题
1. 8-7=-2y
-1=-2y
1/2=y
2. 1/9=x/3-1/6
1/9+1/6=x/3
2/18+3/18=x/3
5/18=6x/18
5=6x
x=5/6