21. Given two different quadratic trinomials $f(x)$ and $g(x)$, whose leading coefficients are equal to one. It is known that $f(19)+f(92)=g(19)+g(92)$. For which $x$ is the equality $f(x)=g(x)$ satisfied?
92.21. Answer. Only at $x=55 \frac{1}{2}$.