Answer
a) $\{x|x$ is a non-negative multiple of 3 that is less than or equal to 12$\}$
b) $\{x| -3\leq x \leq 3, x\in \mathbb{Z}\}$
c) $\{x|x$ is a letter of the English alphabet between m and p$\}$
Work Step by Step
Here, we want to use set builder notation to give descriptions of
a) $\{0, 3, 6, 9, 12\}$
b) $\{-3, -2, -1, 0, 1, 2, 3\}$
c) $\{m, n, o, p\}$.
To do so, we use $\{x|x$ satisfies this/these condition(s)$\}$ notation, as developed in the text