[tex]7. \\J = \frac{2}{5}mR^2 /*5\\5J = 2mR^2 / :2R^2\\m = \frac{5J}{2R^2}[/tex]
[tex]8. \\x-\frac{9x+1}{2} = \frac{1}{5}\\\frac{2x-(9x+1)}{2} = \frac{1}{5}\\\frac{2x-9x-1}{2} = \frac{1}{5} /2\\-7x-1 = \frac{2}{5}\\-7x=\frac{2}{5} + \frac{5}{5}\\-7x=\frac{7}{5} / * - \frac{1}{7}\\x = -\frac{1}{5}[/tex]
