If the two angles are complementary, it means that their measures add up to 90 degrees. The measures of the angles are given as \( 3x \) and \( 4x + 1 \).
Therefore, the equation that represents the relationship between the two angles is:
\[ 3x + (4x + 1) = 90 \]
Simplifying this equation:
\[ 3x + 4x + 1 = 90 \] \[ 7x + 1 = 90 \]
Thus, the correct simplified equation corresponding to the measures of the angles is:
\((7x + 1)° = 90°\)