Ответ:

[tex]a - 3b = 5 \\ 3a + 2b = 16 \\ \\ 3a - 9b = 15 \\ - \\ 3a + 2b = 16 \\ \\ - 11b = - 1 \\ b = \frac{1}{11} \\ \\ a - \frac{3}{11} = 5 \\ a = 5 \frac{3}{11} [/tex]