Question

first, find ( mangle khl).( mangle khl=square^{circ})

Explanation:

Step1: Identify the relationship between angles

Angles \( \angle KHL \) and \( 51^{\circ} \) are supplementary (they form a linear pair).

Step2: Use the supplementary - angle formula

If two angles \( \alpha \) and \( \beta \) are supplementary, then \( \alpha+\beta = 180^{\circ} \). Let \( \alpha=m\angle KHL \) and \( \beta = 51^{\circ} \). So, \( m\angle KHL+51^{\circ}=180^{\circ} \).

Step3: Solve for \( m\angle KHL \)

Subtract \( 51^{\circ} \) from both sides of the equation: \( m\angle KHL=180^{\circ}-51^{\circ} \).

Answer:

\( 129 \)