To determine the equation for the angle measures, we start by knowing the angles formed at point B:
- Angle A B C measures 90 degrees.
- Angle A B D measures 4x degrees.
- Angle D B C measures (7x - 9) degrees.
Since angles A B D and D B C, along with angle A B C, make up the 90 degrees at point B, we can set up the equation:
\[ \text{Angle A B D} + \text{Angle D B C} = \text{Angle A B C} \]
Substituting the angle measures into the equation, we have:
\[ 4x + (7x - 9) = 90 \]
This equation represents the relationship between the angles around point B. You can simplify it further to solve for x if needed.
In the format requested, your placeholder equation could be:
(4x)° + (7x - 9)° = 90°.