[tex]a) \\ \\ \frac{1}{12} + \frac{4}{5} \div ( \frac{1}{2} - \frac{1}{3}) = \\ \\ \frac{1}{12} + \frac{4}{5} \div \frac{1}{6} = \\ \\ \frac{1}{12} + \frac{4}{5} \times 6 = \frac{1}{12} + \frac{24}{5} = \frac{293}{60} \\ \\ b) \\ \\ 2 \div ( \frac{2}{3}) ^{2} + \frac{11}{5} \div \frac{11}{10} = \\ \\ 2 \div \frac{ {2}^{2} }{3 ^{2} } + \frac{11}{5} \div \frac{11}{10} = \\ \\ 2 \div \frac{4}{9} + \frac{11}{5} \div \frac{11}{10} = \\ \\ 2 \times \frac{9}{4} + \frac{11}{5} \div \frac{11}{10} = \\ \\ \frac{18}{4} + \frac{11}{5} \div \frac{11}{10} = \\ \\ \frac{9}{2} + \frac{11}{5} \div \frac{11}{10} = \\ \\ \frac{9}{2} + \frac{11}{5} \times \frac{10}{11} = \frac{9}{2} + \frac{11 \times 10}{5 \times 10} = \frac{9}{2} + \frac{110}{55} = \frac{9}{2} + 2 = \frac{13}{2} \\ \\ c) \\ \\ ( \frac{1}{4} + \frac{7}{6}) \times \frac{15}{34} + \frac{3}{2} \times ( \frac{1}{3} - \frac{1}{21}) = \\ \\ \frac{17}{12} \times \frac{15}{34} + \frac{3}{2} \times \frac{6}{21} = \\ \\ \frac{17 \times 15}{12 \times 34} + \frac{3}{2} \times \frac{6}{21} = \\ \\ \frac{255}{408} + \frac{3}{2} \times \frac{6}{21} = \\ \\ \frac{5}{8} + \frac{3}{2} \times \frac{6}{21} = \\ \\ \frac{5}{8} + \frac{3 \times 6}{2 \times 21} = \frac{5}{8} + \frac{18}{42} = \frac{5}{8} + \frac{3}{7} = \frac{59}{56} \\ \\ d) \\ \\ 12.9 + 1.8 \times 7 = 12.9 + 12.6 = 25.5 [/tex]
