Two angles are complementary when the sum of their measures equals 90 degrees. Given the measures of the angles as \( (x - 6)^\circ \) and \( (3x + 3)^\circ \), we can set up the equation as follows:
\[ (x - 6) + (3x + 3) = 90 \]
Now, simplify the left side of the equation:
\[ x - 6 + 3x + 3 = 90 \] \[ 4x - 3 = 90 \]
Now, we can isolate \( 4x \) by adding 3 to both sides:
\[ 4x = 90 + 3 \] \[ 4x = 93 \]
The simplified equation representing the relationship between the angles is:
\[ 4x - 3 = 90 \]
Therefore, the correct response is:
4x°−3°=90°.