To find the equation to solve for \( x \) given that the angles \( m∠ABC \) and \( m∠CBD \) are supplementary, you need to remember that supplementary angles add up to \( 180° \).
Given:
- \( m∠ABC = 135° \)
- \( m∠CBD = 9x° \)
Since they are supplementary, you can set up the equation as follows:
\[ m∠ABC + m∠CBD = 180° \]
Substituting the values gives:
\[ 135° + 9x° = 180° \]
To isolate \( x \), you can rearrange it to:
\[ 9x° + 135° = 180° \]
Thus, the correct equation to solve for \( x \) is:
Response: 9x° + 135° = 180°