Какое число можно записать вместо х, чтобы верным стало равенство: а) \(\frac{x}{15} = \frac{1}{5}\); б) \(\frac{10}{12} = \frac{5}{x}\); в) \(\frac{8}{x} = \frac{2}{4}\); г) \(\frac{18}{27} = \frac{x}{3}\)?

Решаем уравнения:

1. а) \(\frac{x}{15} = \frac{1}{5}\)
   \(5x = 15\)
   \(x = \frac{15}{5}\)
   \(x = 3\)
2. б) \(\frac{10}{12} = \frac{5}{x}\)
   \(10x = 12 \times 5\)
   \(10x = 60\)
   \(x = \frac{60}{10}\)
   \(x = 6\)
3. в) \(\frac{8}{x} = \frac{2}{4}\)
   \(2x = 8 \times 4\)
   \(2x = 32\)
   \(x = \frac{32}{2}\)
   \(x = 16\)
4. г) \(\frac{18}{27} = \frac{x}{3}\)
   \(27x = 18 \times 3\)
   \(27x = 54\)
   \(x = \frac{54}{27}\)
   \(x = 2\)