Final answer:
Without additional context explaining how EAC and EDC are related, it's not possible to solve for x with the information provided.
Step-by-step explanation:
The student is asking to solve for the value of x given two algebraic expressions: EAC equals 4x and EDC equals 2x + 18. To find the correct value of x, we need to know the relationship between EAC and EDC. Since there's no information provided on the relationship between these two expressions in the question, it can't be determined just from the given expressions. Generally in geometry, if EAC and EDC refer to angles in a certain geometric shape, we would use that relationship to solve for x. For example, if EAC and EDC were angles in the same triangle, their sum would be equal to the third angle of the triangle, assuming we have the measure of that angle. But without additional information or context, we cannot solve for x. The answer will require more details about how EAC and EDC are related within the context of the geometry problem.