角度問題，求x。(20分)

Y+Z+50° = 180 ----------A項
Z = 75° +X -----------------C項

C項代入A項
Y+ 75° +X +50° = 180
Y+ X = 55°
Y = 55° - X ---- F項



3X+4X+X+W=180° -------B項
8X +W=180°

4X + W = 90°--------------D項
W = 90° - 4X

B項代入D項
8X + 90° - 4X=180°
4X = 90°
X = 22.5 ° ----- E 項




E項代入C項
Z= 75° +22.5 °
Z=97.5 °



E 項代入F項
Y = 55° - 22.5 °
Y=32.5 °

X = 22.5 °

w60x 15 y40 z90

x=75
w=45
y=50
z=80

75%lo