Final answer:
The correct equation for the sum of forces in the x-direction, based on the context, should be ΣFx = T1 - T2. Without additional information or figures, we can only assume that the value of T2 is approximately 30.0 N if that were the given value in the problem.
Step-by-step explanation:
The equation for the sum of the forces in the x-direction can be given by ΣFx, which takes into account all the horizontal forces acting on an object. When analyzing forces in equilibrium or those adding up to a resultant force, it's important to consider the direction of each force, since force is a vector quantity. Based on the provided excerpts, specifically the one mentioning -T1x + T2x, the correct form of the equation considering the directions of T1 and T2 would be ΣFx = T1 - T2. In this case, we do not have enough information to determine the exact value of T2 without additional context from the figures mentioned. However, for the purpose of your question, if T2 was equal to 30.0 N, then the option that accurately reflects the direction and magnitude given the information would likely be (b) ΣFx = T1 - T2, T2 ≈ 30.0 N, keeping in mind that without additional information, this is an assumption.