Chapter 2 - Reasoning and Proof - 2-3 Biconditionals and Definitions - Practice and Problem-Solving Exercises - Page 101: 8

Converse: If $2x-5=19$, then $x=12$. Biconditional: $x=12$ if and only if $2x-5=19$.

To write the converse of a conditional statement, write a new conditional statement that switches the hypothesis and conclusion. To write a biconditional, join the hypothesis and the conclusion with the term "if and only if".