[tex]4a + 5y = 1 \: \: | \times 7\\ 5a + 7y = 5 \: \: | \times ( - 5) \\ \\ 28a + 35y = 7 \\ - 25a - 35y = - 25 \\ \\ 28a - 25a = 7 - 25 \\ 3a = - 18 \\ a = - 18 \div 3 \\ a = - 6 \\ \\ 4 \times ( - 6) + 5y = 1 \\ - 24 + 5y = 1 \\ 5y = 1 + 24 \\ 5y = 25 \\ y = 25 \div 5 \\ y = 5[/tex]

Ответ: а = - 6 ; у = 5