Find all $z$ such that neither $2+z-5z$ nor $2-z+8z$ is in the interval $(-7,13]$. Express your answer as an interval or as a union of intervals.
Simplifying, we have −4z≤−9 and 7z≤11. These yield z≥49 and z≤711, which is impossible since 711<49. Hence, there are no solutions.
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