Answer :
So the whole goal of this is to get the variable (z) all by itself on one side with a coefficient (the number in front of the variable (z)) of one. All you have to do is add seven to each side to get z alone and then divide by two:
2z-7< or equal to 1
+7
2z< or equal to 8
/2
z< or equal to 4
2z-7< or equal to 1
+7
2z< or equal to 8
/2
z< or equal to 4
[tex]2z-7\leq1\ \ \ \ |add\ 7\ to\ both\ sides\\\\2z\leq8\ \ \ \ |divide\ both\ sides\ by\ 2\\\\\boxed{z\leq4\to z\in(-\infty;\ 4]}[/tex]
