Номер 405 и 404 зарание спасибо

404.1) 2/7
2) 3 · 5²=3 · 25 =75
3) $\frac{3*7}{11*13} = \frac{21}{143}$
4) 2²=4
5) $\frac{3*11}{14} = \frac{33}{14} = 2 \frac{5}{14}$
6) $\frac{ 2^{2} }{3} = \frac{4}{3} = 1 \frac{1}{3}$
7) $\frac{13}{7} = 1 \frac{6}{7}$
8) $\frac{13}{5} = 2 \frac{3}{5} = 2,6$
9) $\frac{7}{23}$

405
1) $\frac{10*(12+6)}{9*30} = \frac{10*18}{9*30} = \frac{2}{3}$
2) $\frac{19*(4+9)}{38*26} = \frac{19*13}{38*26} = \frac{1}{4}$
3) $\frac{17*(8-3)}{17*6} = \frac{17*5}{17*6} = \frac{5}{6}$
4) $\frac{8*(5+2)}{28*6} = \frac{8*7}{28*6} = \frac{1}{3}$
5) $\frac{16*(28-3)}{16*20} = \frac{16*25}{16*20} = \frac{25}{20} = 1 \frac{1}{4}$
6) $\frac{9*(a+b)}{27c} = \frac{a+b}{3c}$