1. 6=a/4+2
6-2=a/4
4=a/4
4(4)=a
a=16
2. -6+x/4=-5
x/4=-5+6
x/4=1
x=4
3. 9x-7=-7
9x=-7+7
9x=0
x=0
4. 0=4+n/5
-4=n/5
-4(5)=n
n=-20
5. -4=r/20-5
-4+5=r/20
1=r/20
r=20
6. -1=(5+x)/6
-1(6)=5+x
-6=5+x
x=-11
8. 2(n+5)=-2
n+5=-1
n=-6
9. -9x+1=-80
-9x=-81
x=9
10. -6=n/2-10
4=n/2
8=n