To obtain the value of z, the following steps are necessary:
Step 1: Recall the Intersecting Chord Theorem applicable to the question, as below:
Step 2: Apply the theorem to the question, a follows:
[tex]\begin{gathered} z\times3=6\times5 \\ \Rightarrow z\times3=30 \\ \Rightarrow z=\frac{30}{3}=10 \\ \Rightarrow z=10 \end{gathered}[/tex]
Therefore, the value of z is 10 (option C)
