1)
6/b-1=9/7
Add 1 to each side
6/b-1+1=9/7+1
6/b=9/7+7/7
6/b=16/7
Multiply 1/6 to each side
6/b*1/6=16/7*1/6
1/b=16/42
1/b=8/21
b=21/8 or 2 5/8
Check:
6/b-1=9/7
6/21/8-1=9/7
6*8/21-1=9/7
48/21-1=9/7
16/7-1=9/7
16/7-7/7=9/7
9/7=9/7, so x=2 5/8
2)
4/m-8=8/2
Add 8 to each side
4/m-8+8=8/2+8
4/m=8/2+16/2
4/m=24/2
4/m=12
Multiply 1/4 to each side
4/m*1/4=12*1/4
1/m=3
m=1/3
3)
5/6=7n+9/9
5/6=7n+1
7n+1=5/6
Subtract 1 to each side
7n+1-1=5/6-1
7n=5/6-6/6
7n=-1/6
Multiply 1/7 to esvh side
7n*1/7=-1/6*1/7
n=-1/42
4)
4/9=r-3/6
Add 3/6 fo each side
4/9+3/6=r-3/6+3/6
24/54+27/54=r
51/54=r
17/27=r
Hope it help!
