A built$-$up shape that is symmetrical about the y$-$axis BUT NOT symmetrical about the x$-$axis consisting of a PL$18*3/4$ top flange, a PL$10*5/8$ bottom flange, and a PL$60*3/4$ web is used as a beam $($dimensions in inches$).$ A$572$ Grade $50$ is used. Lateral bracing is continuous. Based on this information answer the following question.

Question $1\mathrm{.}5$: What is the controlling plastic section modulus $($Zx$)?[$Enter value in inches$]$