Выполните пожалуйста всеее

1. 1)
$(\frac{a}{3}-\frac{a}{4}) * \frac{2}{a^2} = \frac{4a-3a}{12} * \frac{2}{a^2} = \frac{a}{12} * \frac{2}{a^2} = \frac{1}{6a^2}\\$

2)
$\frac{a-1}{3a} : (1 - \frac{1}{a}) = \frac{a-1}{3a} : \frac{a-1}{a} = \frac{a-1}{3a} * \frac{a}{a-1} = \frac13\\$

3)
$(1+\frac{y}{x}) : (1-\frac{y}{x}) = \frac{x+y}{x} : \frac{x-y}{x} = \frac{x+y}{x} * \frac{x}{x-y} = \frac{x+y}{x-y}\\$

2. 1)
$\frac{a}{1-b}+\frac{a-ab}{b^2-1} * \frac{b+1}{a} = \frac{a(1-b)}{(b-1)(b+1)} * \frac{b+1}{a} - \frac{a}{b-1} = -\frac{a(b-1)}{(b-1)(b+1)} * \frac{b+1}{a} - \frac{a}{b-1} = \\\\ = -1-\frac{a}{b-1} = \frac{1-b-a}{b-1}$

2)
$\frac{a}{a+2}:\frac{a^2+3a}{a^2-4}-\frac{a}{a+3} = \frac{a}{a+2}*\frac{(a-2)(a+2)}{a(a+3)} - \frac{a}{a+3} = \frac{a+2}{a+3} - \frac{a}{a+3} = \frac{a+2-a}{a+3} = \\\\ = \frac{2}{a+3}\\$

3.
$1-\frac{1}{1-\frac{1}{x-3}} = 1 - \frac{1}{\frac{x-4}{x-3}} = 1-\frac{x-3}{x-4} = \frac{x-4-x+3}{x-4} = -\frac{1}{x-4}\\$