Final answer:
Without context or an accompanying figure for the geometry or algebra problem, it is not possible to accurately determine the length of segment AC.
Step-by-step explanation:
The question asks to determine the length of segment AC without providing a figure or additional context. It appears to be a geometry or algebra problem, and without the necessary context or accompanying figure, we cannot accurately determine the length of segment AC. However, the question might be related to a previous part or example where expressions were given for segments, such as 'If /1 = 5 A and 13 = -2 A, then 12 will be equal to'. If this is the case, and segment AC corresponds to one of these algebraic expressions, we may be able to solve for AC using the given information.