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Problem 276: (2022 AMC 10a, 25)
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 $\frac{1}{4}$ of the lattice points contained in $R \cup S.$ See the figure (not drawn to scale). 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 $T$? $\textbf{(A) }336\qquad$ $\textbf{(B) }337\qquad$ $\textbf{(C) }338\qquad$ $\textbf{(D) }339\qquad$ $\textbf{(E) }340$
Solution
Exercise 276: Solution
Squares $R$, $S$, and $T$ have integer-coordinate vertices and bottom edges on the $x$-axis. Square $R$ has side length $8$ and lies to the right of the $y$-axis, with its left edge on the $y$-axis. Square $S$ has side length $6$ and lies to the left of the $y$-axis, with its right edge on the $y$-axis. Square $T$ has side length $4$, with its bottom edge from $(-3,0)$ to $(1,0)$. How many lattice points belong to exactly one of $R$, $S$, and $T$?
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