4. Упростим выражение \(\frac{6c-c^2}{1-c} : \frac{c^2}{1-c}\):
$$ \frac{6c-c^2}{1-c} : \frac{c^2}{1-c} = \frac{c(6-c)}{1-c} \cdot \frac{1-c}{c^2} = \frac{6-c}{c} $$
$$ \frac{6 - 2.4}{2.4} = \frac{3.6}{2.4} = \frac{36}{24} = \frac{12 \cdot 3}{12 \cdot 2} = \frac{3}{2} = 1.5 $$
Ответ: 1.5