Помогите срочно пж по братске

$1. a) \frac{5ab}{15b} = \frac{5a}{3}$

$b) \frac{6m(2 -n)}{3m ^{2}(n - 2) } = \frac{-2(n - 2)}{m(n - 2)} = -\frac{2}{m}$

2. $a) \frac{12x + 3}{24 x^{2} + 6x} = \frac{12x + 3}{2x(12x + 3)} = \frac{1}{2x}$

$b) \frac{y + 5}{y ^{2}+10y + 25 } = \frac{y +5}{(y+5) ^{2} } = \frac{1}{y+5}$

$B) \frac{ a^{2}-4a + 4 }{a ^{2} -4}= \frac{(a - 2) ^{2} }{(a - 2)(a + 2)} = \frac{a- 2}{a + 2}$

$r) \frac{n ^{2}-n + 1 }{n ^{3} -n ^{2}+n } = \frac{n ^{2}-n + 1 }{n(n ^{2} -n +1)} = \frac{1}{n}$

3. $\frac{9 x^{2} -1}{1+6x + 9 x^{2} } = \frac{(3x - 1)(3x + 1)}{(1 + 3x) ^{2} } = \frac{3x - 1}{1 + 3x}$

При $x = \frac{5}{6}$ :

$\frac{3x - 1}{1 + 3x} = \frac{ \frac{5}{6}*3 - 1 }{ \frac{5}{6}*3 + 1 } = \frac{2,5 - 1}{2,5 + 1} = \frac{1,5}{3,5} = \frac{3}{7}$