To find the equation for the two supplementary angles, we start by recalling that supplementary angles add up to 180°.
Given:
- \( m∠ABC = 135° \)
- \( m∠CBD = 9x° \)
Since these angles are supplementary, we can write the equation: \[ m∠ABC + m∠CBD = 180° \]
Substituting the given values into the equation: \[ 135° + 9x° = 180° \]
To simplify the problem, we subtract 135° from both sides: \[ 9x° = 180° - 135° \]
Therefore, the correct equation to solve for \( x \) is: \[ 9x° + 135° = 180° \]
This confirms that the response is: 9x° + 135° = 180°.