How to read variables having superscript? Also how to read those with both super- and subscript?

Question

To read $x_i$, we say "$x$ sub $i$". How do we read $x^i$ where $i$ is not a exponent number and is just a superscript for the variable $x$? How do we read a variable when having both super- and subscript as in $x_i^n$?