Let $R,S,$ and $T$ be squares that have vertices at lattice points (i.e., points whose coordinates are both integers) in the coordinate plane, together with their interiors. The bottom edge of each square is on the $x$-axis. The left edge of $R$ and the right edge of $S$ are on the $y$-axis, and $R$ contains $\frac{9}{4}$ as many lattice points as does $S$. The top two vertices of $T$ are in $R\cup S$, and $T$ contains all of the lattice points contained in $R\cup S$. The fraction of lattice points in $S$ that are in $S\cap T$ is $27$ times the fraction of lattice points in $R$ that are in $R\cap T$. What is the minimum possible value of the edge length of $R$ plus the edge length of $S$ plus the edge length of $T$?