Firstly we are going to simplify both sides of this equation so:
1−z/5=9
So lets simplify 1-z/5=9:
1+−1/5z=9
−1/5z+1=9
Second we are going to subtract 1 from both of the sides so:
−1/5z+1−1=9−1
−1/5z=8
Finally we are going to multiply both of the sides by 5/(-1):
(5/−1)*(−1/5z)=(5/−1)*(8)
And now your final answer shall be:
z=−40
I hope this helps!