1)

[tex]6 \frac{7}{8} - 3 \frac{1}{3} + 5 \frac{5}{16} = 6 \frac{42}{48} - 3 \frac{16}{48} + 5 \frac{15}{48} = 11 \frac{57}{48} - 3 \frac{16}{48} = 8 \frac{41}{48} [/tex]

2)

[tex]5 \frac{8}{15} + 4 \frac{7}{12} - 3 \frac{19}{20} = 5 \frac{32}{60} + 4 \frac{35}{60} - 3 \frac{57}{60} = 9 \frac{67}{60} - 3 \frac{57}{60} =\\= 6 \frac{10}{60} = 6 \frac{1}{6} [/tex]

3)

[tex]5 \frac{9}{14} - 2 \frac{3}{7} + 6.7 = 5 \frac{45}{70} - 2 \frac{30}{70} + 6 \frac{49}{70} = 3 \frac{15}{70} + 6 \frac{49}{70 } =\\= 9 \frac{64}{70} = 9 \frac{32}{35} [/tex]

4)

[tex](36 \frac{2}{3} + 3\frac{1}{8} ) - (18 - 10 \frac{5}{9} ) = 32 \frac{25}{72} \\ 1) \: 36 \frac{2}{3} + 3 \frac{1}{8 } = 36 \frac{16}{24} + 3 \frac{3}{24 } = 39\frac{19}{24} \\ 2) \: 18 - 10 \frac{5}{9} = 17 \frac{9}{9} - 10 \frac{5}{9} = 7 \frac{4}{9} \\ 3) \: 39 \frac{19}{24} - 7 \frac{4}{9} = 39 \frac{57}{72} - 7 \frac{32}{72} = 32 \frac{25}{72} [/tex]

5)

[tex]20 \frac{7}{18} - (15 \frac{5}{6} - 9 \frac{25}{27} ) = 14 \frac{13}{27} \\ 1) \: 15 \frac{5}{6} - 9 \frac{25}{27} = 15 \frac{45}{54} - 9 \frac{50}{54} = 14\frac{99}{54} - 9 \frac{50}{54} = 5 \frac{49}{54} \\ 2) \: 20 \frac{7}{18} - 5\frac{49}{54} = 20 \frac{21}{54} - 5\frac{49}{54} = 19 \frac{75}{54} - 5 \frac{49}{54} = 14 \frac{26}{54} =\\= 14 \frac{13}{27} [/tex]