find the missing angle

Explanation:

Step1: Use the property of adjacent angles on a straight line

Adjacent angles on a straight line sum to (180^{\circ}). So, (y + 77^{\circ}=180^{\circ}).

Step2: Solve for (y)

Subtract (77^{\circ}) from both sides of the equation: (y = 180^{\circ}-77^{\circ}). [y=103^{\circ}]

Answer:

(103)