Вычислите: 12) а) (3 16/27 + 1 17/27) − (2 25/36 + 1 7/36); б) (3 25/48 − 1 35/48) + (4 65/72 − 2 68/72); в) (2 8/35 − 1 13/35) + (3 20/49 − 2 27/49); г) (4 7/15 + 2 11/15) − (3 7/30 + 1 29/30).

а) \((3\frac{16}{27}+1\frac{17}{27})-(2\frac{25}{36}+1\frac{7}{36})=5\frac{33}{27}-4\frac{32}{36}=6\frac{1}{9}-4\frac{8}{9}=1\frac{2}{9}\).

б) \((3\frac{25}{48}-1\frac{35}{48})+(4\frac{65}{72}-2\frac{68}{72})=1\frac{38}{48}+1\frac{141}{72}=1\frac{19}{24}+2\frac{23}{24}=4\frac{5}{6}\).

в) \((2\frac{8}{35}-1\frac{13}{35})+(3\frac{20}{49}-2\frac{27}{49})=\frac{30}{35}+\frac{140}{49}=\frac{6}{7}+2\frac{6}{49}=3\frac{48}{49}\).

г) \((4\frac{7}{15}+2\frac{11}{15})-(3\frac{7}{30}+1\frac{29}{30})=7\frac{18}{15}-5\frac{36}{30}=8\frac{1}{5}-6\frac{1}{5}=2\).

Ответ: а) \(1\frac{2}{9}\); б) \(4\frac{5}{6}\); в) \(3\frac{48}{49}\); г) \(2\).