Given Expression $=\dfrac{(753)^{2}+(247)^{2}-(753 \times 247)}{(753)^{3}+(247)^{3}}=\dfrac{a^{2}+b^{2}-ab}{a^{3}+b^{3}}$, where $a=753$ and $b=247$, $=\dfrac{1}{a+b}=\dfrac{1}{753+247}=\dfrac{1}{1000}$.
Explanation as extracted from the printed page; notation may be imperfect.