124. Найдите значение выражения: а) 3$$\frac{3}{7}$$x – (1$$\frac{3}{14}$$x + $$\frac{8}{21}$$x), если x = 24; x = $$\frac{2}{11}$$. б) а – ($$\frac{1}{15}$$а + $$\frac{3}{10}$$а), если а = 30; а = 1$$\frac{11}{19}$$.

а) 3$$\frac{3}{7}$$x – (1$$\frac{3}{14}$$x + $$\frac{8}{21}$$x), если x = 24; x = $$\frac{2}{11}$$.

1) x = 24

3$$\frac{3}{7}$$x – (1$$\frac{3}{14}$$x + $$\frac{8}{21}$$x) = $$\frac{24}{7}$$x - ($$\frac{17}{14}$$x + $$\frac{8}{21}$$x) = $$\frac{24}{7}$$x - $$\frac{17}{14}$$x - $$\frac{8}{21}$$x = ($$\frac{24}{7}$$ - $$\frac{17}{14}$$ - $$\frac{8}{21}$$)x = ($$\frac{24\cdot6}{7\cdot6}$$ - $$\frac{17\cdot3}{14\cdot3}$$ - $$\frac{8\cdot2}{21\cdot2}$$)x = ($$\frac{144}{42}$$ - $$\frac{51}{42}$$ - $$\frac{16}{42}$$)x = $$\frac{144-51-16}{42}$$x = $$\frac{77}{42}$$x = $$\frac{11}{6}$$x = $$\frac{11}{6}$$\cdot$$24 = 11$$\cdot$$4 = 44

2) x = $$\frac{2}{11}$$

$$\frac{11}{6}$$x = $$\frac{11}{6}$$\cdot$$\frac{2}{11}$$ = $$\frac{1}{3}$$

б) а – ($$\frac{1}{15}$$а + $$\frac{3}{10}$$а), если а = 30; а = 1$$\frac{11}{19}$$.

1) a = 30

a – ($$\frac{1}{15}$$а + $$\frac{3}{10}$$а) = a - $$\frac{1}{15}$$а - $$\frac{3}{10}$$а = (1 - $$\frac{1}{15}$$ - $$\frac{3}{10}$$)a = ($$\frac{30}{30}$$ - $$\frac{2}{30}$$ - $$\frac{9}{30}$$)a = $$\frac{30-2-9}{30}$$a = $$\frac{19}{30}$$a = $$\frac{19}{30}$$\cdot$$30 = 19

2) a = 1$$\frac{11}{19}$$ = $$\frac{30}{19}$$

$$\frac{19}{30}$$a = $$\frac{19}{30}$$\cdot$$\frac{30}{19}$$ = 1

Ответ: а) 44; $$\frac{1}{3}$$. б) 19; 1