Final answer:
Without the diagram provided in the question, it is impossible to determine which equation is correct. However, based on practice test information, the student may be looking at linear equations or geometric angle sums, which can include linear equations or expressions equaling 180 degrees.
Step-by-step explanation:
To answer the student's question regarding which equation can be concluded from the diagram, we would need to see the diagram in question. Without the diagram, it's impossible to determine which statement is correct. However, based on the information provided in the practice test references, it seems the student is dealing with linear equations and the calculation of variables in different scenarios.
For instance, if the diagram relates to a linear equation, we might expect an equation similar to the examples in Practice Test 4, 12.1 Linear Equations, where linear equations like y = -3x or y = 0.2 + 0.74x are given. These equations are clear in having a constant rate of change, characteristic of linear relationships.
Alternatively, if the question pertains to geometry and the calculation of angles, option D, which states (3y + 20) + (5y - 16) = 180, might relate to the sum of angles in a geometric figure such as a triangle or quadrilateral.