Two ordered pairs are equal if and only if their corresponding first elements are equal and their corresponding second elements are equal. Setting $x/3 + 1 = 5/3$ gives $x/3 = 5/3 - 1 = 2/3$, so $x = 2$. Setting $y - 2/3 = 1/3$ gives $y = 1/3 + 2/3 = 1$. Therefore, $x=2$ and $y=1$. Other options fail to satisfy both linear equations simultaneously.