[tex]\displaystyle a).\frac{1}{5} - \frac{1}{2} + \frac{1}{4} = \frac{4}{20} - \frac{10}{20} + \frac{5}{20} =- \frac{1}{20} \\ \\ b). \frac{2}{3} - \frac{1}{6} - \frac{3}{4} = \frac{8}{12} - \frac{2}{12} - \frac{9}{12} =- \frac{3}{12} =- \frac{1}{4} \\ \\ c).- \frac{7}{12} + \frac{1}{3} + \frac{1}{4} =- \frac{7}{12} + \frac{4}{12} + \frac{3}{12} =0 \\ \\ d). \frac{2}{5} - \frac{1}{2} - \frac{7}{10} = \frac{4}{10} - \frac{5}{10} - \frac{7}{10} =- \frac{8}{10} =- \frac{4}{5} [/tex]
[tex]\displaystyle e). \frac{1}{21} -1 \frac{4}{7} - \frac{2}{-3} = \frac{1}{21} - \frac{11}{7} + \frac{2}{3} = \frac{1}{21} - \frac{33}{21} + \frac{14}{21} =- \frac{18}{21} =- \frac{6}{7} \\ \\ f).2-3 \frac{1}{4} +2 \frac{1}{8} =2- \frac{13}{4} + \frac{17}{8} = \frac{16}{8} - \frac{26}{8} + \frac{17}{8} = \frac{7}{8} [/tex]
