If the two angles are complementary, their measures must add up to 90 degrees. Given the angles \((x - 6)^\circ\) and \((3x + 3)^\circ\), we can write the equation:
\[ (x - 6) + (3x + 3) = 90 \]
Simplifying this, we combine like terms:
\[ x - 6 + 3x + 3 = 90 \]
\[ 4x - 3 = 90 \]
So the simplified equation for the angles is:
\[ 4x - 3 = 90 \]
The correct response is:
4x°−3°=90°