Answer:
m∠D = 54°
Explanation:
The sum of the measures of the interior angles of a triangle is 180°.
The sum of the measures of an interior angle and its corresponding exterior angle is 180°.
With this knowledge, we can construct the equation:
50° + (3x + 18)° + (180 - (8 + 8x))° = 180°
and solve for x.
50° + (3x + 18)° + (180 - 8 - 8x)° = 180°
(50 + 18 + 180 - 8)° + (3x - 8x)° = 180°
240° - 5x° = 180°
5x° = 240° - 180°
5x° = 60°
x° = 12°
Now, we can solve for m∠D by plugging in the x value that we solved for.
m∠D = (3x + 18)°
m∠D = 3(12)° + 18°
m∠D = 36° + 18°
m∠D = 54°