И) 1 7/9 + 3 4/7

И) \( 1\frac{7}{9} + 3\frac{4}{7} = (1+3) + (\frac{7}{9} + \frac{4}{7}) = 4 + \frac{7 · 7}{9 · 7} + \frac{4 · 9}{7 · 9} = 4 + \frac{49}{63} + \frac{36}{63} = 4 + \frac{49+36}{63} = 4 + \frac{85}{63} = 4 + 1\frac{22}{63} = 5\frac{22}{63} \)