We are asked to find the values needed for the length CB
The coordinates of points C and B are given as
C(-a, -5b)
Recall that the distance formula is given by

For the given case,

Let us substitute these coordinates into the above distance formula
![\begin{gathered} CB=\sqrt[]{({x_2-x_1})^2+({y_2-y_1})^2} \\ CB=\sqrt[]{({3a_{}-(-a)})^2+({b_{}-(-5b)_{}})^2} \\ CB=\sqrt[]{({3a_{}+a})^2+({b_{}+5b})^2} \\ CB=\sqrt[]{({4a})^2+({6b})^2} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/m9zqghvdroy2my7jxdjr0yah04m14bgnff.png)
Therefore, the required values are
![CB=\sqrt[]{({4a})^2+({6b})^2}](https://img.qammunity.org/2023/formulas/mathematics/high-school/trvf4i1lxa7mv91w5o52b9deox4h8hisdv.png)