7. 1) 4 \frac{13}{17} + 5 \frac{4}{17}; 2) 3 \frac{8}{11} + 2 \frac{6}{11}; 3) 1 - \frac{16}{21}; 4) 5 - 2 \frac{3}{8}; 5) 8 \frac{4}{9} - 3 \frac{7}{9}; 6) 12 \frac{19}{44} - 6 \frac{37}{44}.

1) $$4 \frac{13}{17} + 5 \frac{4}{17} = (4 + 5) + (\frac{13}{17} + \frac{4}{17}) = 9 + \frac{17}{17} = 9 + 1 = 10$$

2) $$3 \frac{8}{11} + 2 \frac{6}{11} = (3 + 2) + (\frac{8}{11} + \frac{6}{11}) = 5 + \frac{14}{11} = 5 + 1 \frac{3}{11} = 6 \frac{3}{11}$$

3) $$1 - \frac{16}{21} = \frac{21}{21} - \frac{16}{21} = \frac{5}{21}$$

4) $$5 - 2 \frac{3}{8} = 4 \frac{8}{8} - 2 \frac{3}{8} = (4 - 2) + (\frac{8}{8} - \frac{3}{8}) = 2 + \frac{5}{8} = 2 \frac{5}{8}$$

5) $$8 \frac{4}{9} - 3 \frac{7}{9} = 7 \frac{13}{9} - 3 \frac{7}{9} = (7 - 3) + (\frac{13}{9} - \frac{7}{9}) = 4 + \frac{6}{9} = 4 + \frac{2}{3} = 4 \frac{2}{3}$$

6) $$12 \frac{19}{44} - 6 \frac{37}{44} = 11 \frac{63}{44} - 6 \frac{37}{44} = (11 - 6) + (\frac{63}{44} - \frac{37}{44}) = 5 + \frac{26}{44} = 5 + \frac{13}{22} = 5 \frac{13}{22}$$

Ответ: 1) 10; 2) 6 \frac{3}{11}; 3) \frac{5}{21}; 4) 2 \frac{5}{8}; 5) 4 \frac{2}{3}; 6) 5 \frac{13}{22}.