Răspuns:
12.a)
[tex]( \frac{7}{8} - \frac{1}{8} ) + \frac{1}{4} = \\ = \frac{6}{8} + \frac{2}{8} = \\ = \frac{8}{8} = 1[/tex]
b)
[tex]( \frac{5}{6} + \frac{7}{6}) - \frac{1}{7} = \\ = \frac{12}{6} - \frac{1}{7} = \\ = \frac{84}{42} - \frac{6}{42} = \\ = \frac{78}{42} = \frac{13}{7} [/tex]
c)
[tex]( \frac{7}{3} - \frac{4}{3} ) - \frac{12}{13} = \\ = \frac{3}{3} - \frac{12}{13} = \\ = \frac{1}{13} [/tex]
d)
[tex] \frac{4}{3} - ( \frac{9}{11} + \frac{2}{11} ) = \\ = \frac{4}{3} - \frac{11}{11} = \\ = \frac{1}{3} [/tex]
13.a)
[tex]6 \frac{2}{7} - 4 \frac{1}{7} = \\ = \frac{6 \times 7 + 2}{7} - \frac{7 \times 4 + 1}{7} = \\ = \frac{44}{7} - \frac{29}{7} = \\ = \frac{15}{7} [/tex]
b)
[tex]12 \frac{1}{9} - 5 \frac{4}{9} = \\ = \frac{119}{9} - \frac{49}{9} = \\ = \frac{70}{9} [/tex]
c)
[tex]8 \frac{4}{5} - 3 \frac{1}{5} = \\ = \frac{44}{5} - \frac{16}{5} = \\ = \frac{28}{5} [/tex]
d)
[tex]18 \frac{2}{11} - 7 \frac{5}{11} = \\ = \frac{200}{11} - \frac{82}{11} = \\ = \frac{118}{11} [/tex]
