\[\left( \frac{c - 7\sqrt{b}}{\sqrt{\text{cb}} - b} - \frac{7\sqrt{c} + \sqrt{b}}{\sqrt{\text{cb}} - c} \right)\ :\frac{c + b}{\sqrt{c} - \sqrt{b}} =\]
\[= \frac{c\sqrt{c} + b}{\sqrt{\text{cb}}(c + b)}\]
\[1)\ \frac{c - 7\sqrt{b}}{\sqrt{\text{cb}} - b} - \frac{7\sqrt{c} + \sqrt{b}}{\sqrt{\text{cb}} - c} =\]
\[= \frac{c - 7\sqrt{b}}{\sqrt{b}\left( \sqrt{c} - \sqrt{b} \right)} - \frac{7\sqrt{c} + \sqrt{b}}{\sqrt{c}\left( \sqrt{b} - \sqrt{c} \right)} =\]
\[= \frac{c - 7{\sqrt{b}}^{\backslash\text{√}c}}{\sqrt{b}\left( \sqrt{c} - \sqrt{b} \right)} + \frac{7\sqrt{c} + {\sqrt{b}}^{\backslash\sqrt{b}}}{\sqrt{c}\left( \sqrt{c} - \sqrt{b} \right)} =\]
\[= \frac{c\sqrt{c} - 7\sqrt{\text{cb}} + 7\sqrt{\text{cb}} + b}{\sqrt{\text{cb}}\left( \sqrt{c} - \sqrt{b} \right)} =\]
\[= \frac{c\sqrt{c} + b}{\sqrt{\text{cb}}\left( \sqrt{c} - \sqrt{b} \right)}\]
\[2)\ \frac{c\sqrt{c} + b}{\sqrt{\text{cb}}\left( \sqrt{c} - \sqrt{b} \right)}\ :\frac{c + b}{\sqrt{c} - \sqrt{b}} =\]
\[= \frac{\left( c\sqrt{c} + b \right)\left( \sqrt{c} - \sqrt{b} \right)}{\sqrt{\text{cb}}\left( \sqrt{c} - \sqrt{b} \right)(c + b)} =\]
\[= \frac{c\sqrt{c} + b}{\sqrt{\text{cb}}(c + b)}\]