Question

Здравствуйте!Помогите,пожалуйста ​

Answer 1

$\frac{1 - 7c}{7} \div \frac{63c - 9}{9c} = \frac{1 - 7c}{7} \times \frac{9c}{9 \times (7c - 1)} =$

$= \frac{1 - 7c}{7} \times \frac{c}{7c - 1} = \frac{1 - 7c}{7} \times ( - \frac{c}{1 - 7c} ) = - \frac{c}{7}$