Final answer:
The question involves using Coulomb's Law to calculate the resultant electric force on a charge within a system of point charges and employing vector addition if necessary.
Step-by-step explanation:
The student's question is related to the calculation of the magnitude of the electric force on a charge within a system of multiple point charges. Specifically, this involves using Coulomb's Law, which states that the electric force between two point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them. In these examples with various point charges located at different positions along the x-axis, one would need to calculate the resultant force on a specific charge by considering both the magnitude and direction of the forces exerted by the other charges in the system. Typically, this would require vector addition of forces if the charges are not aligned along the same axis.