а) \(\frac{45}{100} = \frac{45:5}{100:5} = \frac{9}{20}\)
б) \(\frac{75}{1000} = \frac{75:25}{1000:25} = \frac{3}{40}\)
Ответ: а) \(\frac{9}{20}\); б) \(\frac{3}{40}\)