a)
[tex] \frac{2}{3} \times 2.1 + 2 \times (3 \frac{2}{5} + 1.4) = \frac{2}{3} \times \frac{21}{10} + 2 \times ( \frac{17}{5} + \frac{14}{10} ) = \frac{7}{5} + 2 \times ( \frac{34}{10} + \frac{14}{10} ) = \frac{7}{5} + 2 \times \frac{48}{10} = \frac{7}{5} + \frac{48}{5} = \frac{55}{5} = 11[/tex]
b)
[tex](0.4 \times \frac{5}{3} - \frac{2}{9} ) \div 0.25 = ( \frac{4}{10} \times \frac{5}{3} - \frac{2}{9} ) \div \frac{1}{4} = ( \frac{4}{6} - \frac{2}{9} ) \times 4 = ( \frac{36}{54} - \frac{12}{54} ) \times 4 = \frac{24}{54} \times 4 = \frac{24}{27} \times 2 = \frac{48}{27} = 1 \frac{21}{27} = 1 \frac{7}{9} [/tex]
c)
[tex](1.2 + \frac{1}{25} ) \div 0.4 - (1.75 - \frac{5}{4} ) \times \frac{2}{3} = ( \frac{12}{10} + \frac{1}{25} ) \div \frac{4}{10} - ( \frac{7}{4} - \frac{5}{4} ) \times \frac{2}{3} = ( \frac{120}{100} + \frac{4}{100}) \times \frac{10}{4} - \frac{1}{2} \times \frac{2}{3} = \frac{124}{100} \times \frac{10}{4} - \frac{1}{3} = \frac{31}{10} - \frac{1}{3} = \frac{93}{30} - \frac{10}{30} = \frac{83}{30} = 2 \frac{23}{30} [/tex]
d)
[tex] \frac{1}{8} \div 0.3 - (1.75 - \frac{1}{12} ) \times 0.25 = \frac{1}{8} \times \frac{10}{3} - ( \frac{7}{4} - \frac{1}{12} ) \times \frac{1}{4} = \frac{5}{12} - ( \frac{21}{12} - \frac{1}{12} ) \times \frac{1}{4} = \frac{5}{12} - \frac{20}{12} \times \frac{1}{4} = \frac{5}{12} - \frac{5}{12} = 0[/tex]
