Ответ:

[tex]1) \frac{3}{x} - \frac{8}{x} = \frac{3 - 8}{x } = - \frac{5}{x} [/tex]

[tex]2) \frac{12}{a} - \frac{4}{a} = \frac{12 - 4}{a} = \frac{8}{a} [/tex]

[tex]3) \frac{3x + 3}{3x + 15} + \frac{12}{3x + 15} = \frac{3x + 3 + 12}{3x + 15} = \frac{3x + 15}{3x + 15} = 1[/tex]

[tex]4) \frac{14 + x}{14 - 5x} - \frac{6x}{14 - 5x} = \frac{14 + x - 6x}{14 - 5x} = \frac{14 - 5x}{14 - 5x} = 1[/tex]

[tex]5) \frac{25}{y + 5} - \frac{ {y}^{2} }{y + 5} = \frac{25 - {y}^{2} }{y + 5} = \frac{(5 - y)(5 + y)}{y + 5} = 5 - y[/tex]

[tex]6) \frac{ {b}^{2} }{b - 7} - \frac{49}{b - 7} = \frac{ {b}^{2} - 49 }{b - 7} = \frac{(b - 7)(b + 7)}{b - 7} = b + 7[/tex]

Ответ:

1)5 2) 8 3)1 5)5-у 6)b+1

х а