Решите уравнение:
а) $(\frac{2}{3}х - \frac{4}{5}) * 15 = 8$;
б) $(\frac{5}{7} - \frac{2}{3}y) * 21 = 1$;
в) $\frac{2}{3}х + \frac{7}{3}х = 18$;
г) $\frac{7}{12}m + \frac{2}{3}m - \frac{1}{4}m = 7$.
$(\frac{2}{3}х - \frac{4}{5}) * 15 = 8$
$\frac{2}{3}х * 15 - \frac{4}{5} * 15 = 8$
$10х - 12 = 8$
$10х = 8 + 12$
$10х = 20$
$х = 20 : 10 = 2$
$(\frac{5}{7} - \frac{2}{3}y) * 21 = 1$
$\frac{5}{7} * 21 - \frac{2}{3}y * 21 = 1$
$15 - 14y = 1$
$-14y = 1 - 15$
$-14y = -14$
$14y = 14$
$y = 14 : 14 = 1$
$\frac{2}{3}х + \frac{7}{3}х = 18$
$\frac{9}{3}х = 18$
$3х = 18$
$х = 18 : 3 = 6$
$\frac{7}{12}m + \frac{2}{3}m - \frac{1}{4}m = 7$
$\frac{7}{12}m + \frac{8}{12}m - \frac{3}{12}m = 7$
$\frac{12}{12}m = 7$
$m = 7$
Пожауйста, оцените решение
