$\text{The second height is } 10\% \text{ less than the first.}$

$\text{The first height is } 10\% \text{ more than the second.}$

$\text{The second height is } 21\% \text{ less than the first.}$

$\text{The first height is } 21\% \text{ more than the second.}$

$\text{The second height is } 80\% \text{ of the first.}$