Can someone pls help me to solve 15 and 16 and answer 17 I will mark you the brainly pls I will really appreciate

Answer:
15) x = 20
16) y = 45°, z = 30°
17) all 4 corners = 90°, all 4 sides are equal length, diagonals are perpendicular, diagonals bisect the corner angles.
We can't do the extra credit because we do not have a relationship about the side lengths. We just have angle information.
Step-by-step explanation:
15) 2x + 8 = 3x - 12
x = 20
16) 2y = 90°
y = 45°
3z = 90°
z = 30°