To solve for z, let's first use the distributive property on the right side of the equation to make it:
[tex] 5z-14<-28-2z [/tex]
Now, add 2z to both sides to get rid of it on one of the sides:
[tex] 7z-14<-28 [/tex]
In the same manner, add 14 to both sides:
[tex] 7z< -14 [/tex]
Now divide by 7 (you only need to switch the sign if dividing by a negative number - so not in this case):
[tex] z < -\frac{14}{7} [/tex]
[tex] z < -2 [/tex]
Therefore, your answer is: z < -2. Hope I could help you out!