G2.4 Given that $x$ and $y$ are positive integers and $x+y+x y=54$. If $t=x+y$, find the value of $t$.
$\begin{array}{l}1+x+y+x y=55 \\ (1+x)(1+y)=55 \\ 1+x=5,1+y=11 \text { or } 1+x=11,1+y=5 \\ x=4, y=10 \text { or } x=10, y=4 \\ t=14\end{array}$