Răspuns:
[tex] \frac{a + b}{2} = \frac{23}{9} = > a + b = \frac{46}{9} [/tex]
[tex] \frac{b + c}{2} = \frac{31}{9} = > b + c = \frac{62}{9} [/tex]
[tex] \frac{a + c}{2} = \frac{15}{9} = > a + c = \frac{30}{9} [/tex]
[tex]a = \frac{46}{9} - b \\ b = \frac{62}{9} - c \\ = > a = \frac{46}{9} - \frac{62}{9} + c \\ a = c - \frac{16}{9} [/tex]
[tex]9a + 9c = 90 \\ 9a - 9c = - 16 \\ 18a = 74 = > a = \frac{74}{18} = \frac{37}{9} = 4.(1)[/tex]
[tex] - 9a - 9c = - 90 \\ 9a - 9c = - 16 \\ - 18c = - 106 \\ c = \frac{106}{18} = \frac{53}{9} = 5.(8)[/tex]
[tex]b = \frac{62}{9} - \frac{53}{9} = \frac{9}{9} = 1[/tex]
