b) Fill in the following proportions. [1pt each] \[ \frac{C M}{C A}=\frac{M N}{A B}=\frac{C N}{} \]

To fill in the proportions, we need to analyze the relationships between the segments. The proportions can often be found by applying the properties of similar triangles or by using the concept of cross-multiplication. For the proportion \(\frac{C M}{C A} = \frac{M N}{A B} = \frac{C N}{x}\), we need to identify what \(x\) could represent. Based on the consistent ratios, if we denote the lengths of segments appropriately, you're likely looking for a pattern or a missing segment that directly corresponds to \(C N\). Let's say that \(x\) equals the length of \(A N\) in this case, as it maintains the balance of ratios. Thus, you can fill it in as: \(\frac{C M}{C A} = \frac{M N}{A B} = \frac{C N}{A N}\)