1) \(\frac{390}{650} = \frac{39}{65} = \frac{3 \cdot 13}{5 \cdot 13} = \frac{3}{5}\)
2) \(\frac{4550}{5550} = \frac{455}{555} = \frac{91}{111}\)
3) \(\frac{570}{13310} = \frac{57}{1331}\)
4) \(\frac{4200}{4550} = \frac{420}{455} = \frac{84}{91} = \frac{12}{13}\)