2.321 Найдите значение выражения: a) $$ (\frac{61}{64} - \frac{7}{12}) \cdot (\frac{13}{16} + \frac{1}{2}) $$; б) $$ (1 - \frac{11}{17}) \cdot (\frac{3}{5} + \frac{11}{12}) $$; в) $$ (3.5 - 2.9) \cdot (4\frac{1}{22} - 3\frac{7}{33}) $$; г) $$ (5\frac{3}{14} - 4\frac{4}{7}) \cdot (3\frac{5}{9} + 4\frac{11}{15}) $$;

a) $$ (\frac{61}{64} - \frac{7}{12}) \cdot (\frac{13}{16} + \frac{1}{2}) = (\frac{61 \cdot 3 - 7 \cdot 16}{192}) \cdot (\frac{13 + 8}{16}) = (\frac{183 - 112}{192}) \cdot (\frac{21}{16}) = \frac{71}{192} \cdot \frac{21}{16} = \frac{71 \cdot 7}{64 \cdot 16} = \frac{497}{1024} $$; б) $$ (1 - \frac{11}{17}) \cdot (\frac{3}{5} + \frac{11}{12}) = (\frac{17 - 11}{17}) \cdot (\frac{3 \cdot 12 + 11 \cdot 5}{60}) = \frac{6}{17} \cdot \frac{36 + 55}{60} = \frac{6}{17} \cdot \frac{91}{60} = \frac{1}{17} \cdot \frac{91}{10} = \frac{91}{170} $$; в) $$ (3.5 - 2.9) \cdot (4\frac{1}{22} - 3\frac{7}{33}) = 0.6 \cdot (\frac{89}{22} - \frac{106}{33}) = 0.6 \cdot (\frac{89 \cdot 3 - 106 \cdot 2}{66}) = 0.6 \cdot (\frac{267 - 212}{66}) = 0.6 \cdot \frac{55}{66} = 0.6 \cdot \frac{5}{6} = \frac{3}{5} = 0.5 $$; г) $$ (5\frac{3}{14} - 4\frac{4}{7}) \cdot (3\frac{5}{9} + 4\frac{11}{15}) = (\frac{73}{14} - \frac{32}{7}) \cdot (\frac{32}{9} + \frac{71}{15}) = (\frac{73 - 64}{14}) \cdot (\frac{32 \cdot 5 + 71 \cdot 3}{45}) = \frac{9}{14} \cdot (\frac{160 + 213}{45}) = \frac{9}{14} \cdot \frac{373}{45} = \frac{1}{14} \cdot \frac{373}{5} = \frac{373}{70} = 5\frac{23}{70} $$.