70 2:0,3-1:7. 2 20 105x. a) 70=4; 1 6):x=2:3 3 7

a) $$\frac{105}{70} = \frac{x}{4}$$ $$x = \frac{105 \cdot 4}{70} = \frac{105 \cdot 2}{35} = 3 \cdot 2 = 6$$ б) $$1 : x = 2 : 3$$ $$\frac{1}{x} = \frac{2}{3}$$ $$x = \frac{3}{2} = 1,5$$ Ответ: a) x = 6; б) x = 1,5.