Question

решите уравнения; b:25/6=4/7:20/21

Answer 1

$\displaystyle\\\\b:(\frac{25}{6})=\frac{4}{7}: \frac{20}{21}$

По св-ву пропорции:

$\displaystyle\\\\b*\frac{20}{21} =\frac{4}{7}*\frac{25}{6} \\\\\frac{20}{21} b=\frac{100}{42} \\\\\frac{20}{21} b=\frac{50}{21} \\\\b=\frac{50}{21} :\frac{20}{21}\\\\b=\frac{50*21}{21*20} \\\\b=\frac{50}{20} \\\\b=\frac{5}{2} \\\\b=2.5$

Ответ: 2.5