\(\frac{42}{46}+\frac{250}{186}+\left(-\frac{2121}{2323}\right)+\left(-\frac{125125}{143143}\right)\)
\(=\frac{21}{23}+\frac{125}{93}+\left(-\frac{21}{23}\right)+\left(-\frac{125}{143}\right)\)
\(=\left(\frac{21}{23}-\frac{21}{23}\right)+\frac{125}{93}+\left(-\frac{125}{143}\right)\)
\(=0+\frac{125}{93}+\left(-\frac{125}{143}\right)\)
\(=\frac{6250}{13299}\)