To determine the appropriate equation that could be used to solve problems involving the relationships between the angles, it’s important to understand the context of the angles involved.
If we are dealing with two angles where one angle is \( (12 + a) \) and the other is \( (7a + 12) \), and if these angles form a relationship with a right angle (90 degrees), we would typically set up an equation based on the angles summing to 90 degrees or perhaps subtracting from 90 degrees if forming complementary angles.
Let's analyze the given choices:
- A: \( (12 + a) + (7a + 12) = 90 \) — This suggests the angles sum to 90, which fits the pattern of complementary angles.
- B: \( 90 + (12 + a) = (7a + 12) \) — This does not directly relate to the usual angles' relationships.
- C: \( (12 + a) - (7a + 12) = 90 \) — This incorrectly sets up a relationship, as it implies a subtraction resulting in 90.
- D: \( (7a + 12) - 90 = (12 + a) \) — This equation sets one angle less than 90, which is not standard for angles that should sum to 90.
- E: \( (7a + 12) + 90 = (12 + a) \) — This does not fit the context of angles comprehensively.
Given that option A directly implements the condition where two angles sum to 90 degrees, it is the most relevant option here.
Thus, the equation that could be used to solve problems involving the relationships between the angles is:
A (12 + a) + (7a + 12) = 90