Alcohol Phenols And Ethers

An alcohol $X\left(\mathrm{C}_5 \mathrm{H}_{12} \mathrm{O}\right)$ on dehydration gives $Y$ (major product). Reaction of $Y$ with HBr gave $Z\left(\mathrm{C}_5 \mathrm{H}_{11} \mathrm{Br}\right)$, major product). $Z$ undergoes nucleophilic substitution in two steps. What are $X$ and $Y$ ?