Question

решить 7,8,9,10 нечего не понимаю

Answer 1

7)

$5 \frac{5}{6} \div 3 \frac{1}{2} = x \div 15$

$\frac{35}{6} \div \frac{7}{2} = x \div 15$

$\frac{35}{6} \times \frac{2}{7} = \frac{x}{15}$

$\frac{5}{3} = \frac{x}{15}$

$3x = 75$

$x = 25$

8)

$\frac{4}{5} x + 6(3 - \frac{2}{5} x) = 17$

$\frac{4}{5} x + 18 - \frac{12}{5} x = 17$

$\frac{4}{5} x - \frac{12}{5} x = 17 - 18$

$x = 1 \times \frac{5}{8}$

$x = \frac{5}{8}$

9)

$5(x - 7) = 3(x - 4) - 27$

$5x - 35 = 3x - 12 - 27$

$5x - 3x = - 12 - 27 + 35$

$2x = - 4$

$x = - 2$

10)

$\frac{x - 0.8}{x + 0.2} = \frac{6.3}{7.3}$

$- 0.8 \times 7.3 = 0.2 \times 6.3$

$- 5.84 = 1.26$

$x = 1.26 + 5.84 = 7.1$