4. Реши уравнение: a) 3/5 * Х = 3/10 + 2/5; б) 3/9 * Х = 5 5/6 : 7/4

1. a) $$\frac{3}{5} \cdot X = \frac{3}{10} + \frac{2}{5}$$ $$\frac{3}{5} \cdot X = \frac{3}{10} + \frac{2 \cdot 2}{5 \cdot 2}$$ $$\frac{3}{5} \cdot X = \frac{3}{10} + \frac{4}{10}$$ $$\frac{3}{5} \cdot X = \frac{7}{10}$$ $$X = \frac{7}{10} : \frac{3}{5}$$ $$X = \frac{7}{10} \cdot \frac{5}{3}$$ $$X = \frac{7 \cdot 5}{10 \cdot 3}$$ $$X = \frac{7 \cdot 1}{2 \cdot 3}$$ $$X = \frac{7}{6} = 1\frac{1}{6}$$
2. б) $$\frac{3}{9} \cdot X = 5\frac{5}{6} : \frac{7}{4}$$ $$\frac{3}{9} \cdot X = \frac{35}{6} : \frac{7}{4}$$ $$\frac{3}{9} \cdot X = \frac{35}{6} \cdot \frac{4}{7}$$ $$\frac{3}{9} \cdot X = \frac{35 \cdot 4}{6 \cdot 7}$$ $$\frac{3}{9} \cdot X = \frac{5 \cdot 2}{3 \cdot 1}$$ $$\frac{3}{9} \cdot X = \frac{10}{3}$$ $$X = \frac{10}{3} : \frac{3}{9}$$ $$X = \frac{10}{3} \cdot \frac{9}{3}$$ $$X = \frac{10 \cdot 9}{3 \cdot 3}$$ $$X = \frac{10 \cdot 3}{1 \cdot 3}$$ $$X = \frac{10}{1} = 10$$

Ответ:

1. $$1\frac{1}{6}$$
2. $$10$$