3)
-z+7= -8
subtract 7 from each side to then get -z= -15
If you need a positive number for z multiply each side by -1
4)
[tex] \frac{w}{-9} +7=10[/tex]
subtract 7 from each side to get [tex] \frac{w}{-9} =10[/tex]
Then multiply each side by -9 to get W= -90
5)
25=8+[tex] \frac{n}{2} [/tex]
first subtract 8 from each side to get 25=[tex] \frac{n}{2} [/tex]
Now multiply each side by 2 to get 50=n
6)
[tex] \frac{y-8}{3} =-7[/tex]
first multiply each side by three to get y-8= -21
add 8 to each side y= -13
Hope I helped :)