Let $x,$ $y,$ $z$ be real numbers such that $x + y + z = 5$ and $xy + xz + yz = 8.$  Find the largest possible value of $x.$The answer is in the form rac{m}{n}, where gcd(m, n) = 1. Please provide the value of m + n.

Let's think step by step and output the final answer within \boxed{}.
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