Ответ:\(\frac{8x}{12x}=\frac{2}{3}\), при \(x\ne0\).\(\frac{25ax}{45x}=\frac{5a}{9}\), при \(x\ne0\).\(\frac{5kt}{t}=5k\), при \(t\ne0\).\(\frac{6c}{18ac}=\frac{1}{3a}\), при \(a\ne0\) и \(c\ne0\).