Помогите пожалуйста !!!

4.
$\frac{2x-y}{x+y} : \frac{2x-y}{x-y} *\frac{x+y}{x-y} = \frac{2x-y}{x+y} * \frac{x-y}{2x-y} *\frac{x+y}{x-y} = \\ \\ = \frac{1}{x+y} * \frac{x-y}{1} *\frac{x+y}{x-y} = \frac{1}{1} * \frac{x-y}{1} *\frac{1}{x-y} = \frac{1}{1} * \frac{1}{1} *\frac{1}{1} = 1$

при любых х и у

5.
$\frac{1-2x}{3} + \frac{2-3x}{4}+ \frac{x}{5} = \frac{1}{12} \\ \frac{20(1-2x)}{20*3} + \frac{15(2-3x)}{15*4}+ \frac{12x}{12*5} = \frac{5*1}{5*12} \\ \frac{20-40x}{60} + \frac{30-45x}{60}+ \frac{12x}{60} = \frac{5}{60} \\ 20-40x+30-45x+12x = 5 \\ 50-73x=5 \\ -73x=-45 \\$
x=45/73