[math] \newcommand{\NA}{{\rm NA}} \newcommand{\mat}[1]{{\bf#1}} \newcommand{\exref}[1]{\ref{##1}} \newcommand{\secstoprocess}{\all} \newcommand{\NA}{{\rm NA}} \newcommand{\mathds}{\mathbb}[/math]

Let [math]A[/math] and [math]B[/math] be events such that [math]P(A \cap B) = 1/4[/math], [math]P(\tilde A) = 1/3[/math], and [math]P(B) = 1/2[/math]. What is [math]P(A \cup B)[/math]?