∠GHJ and ∠RST are complementary
⇒ ∠GHJ and ∠RST = 90°
And ∠RST and ∠ABC are supplementary
⇒ ∠RST and ∠ABC = 180°
Also, ∠GHJ = x°
⇒ ∠RST = 90° - x°
⇒ ∠ABC = 180° - ∠RST
⇒ ∠ABC = 180° - (90° - x°)
⇒ ∠ABC = 90° + x°
The answer is option "3, 40".
<span>m∠cab = 2x
m∠acb = x + 30
m∠cbd = 5x − 50
Now,
</span>m∠cab + m∠acb = m∠cbd
2x+x+30 = 5x-50
2x+x-5x = -50-30
-2x = -80
x = 40
AD = DB
Angle ADE = Angle CDB
Angle DAE = Angle DBC (Alternate angles)
Angle DEA = Angle DCB (Alternate angles)
Since you have two congruent angles and one congruent side, triangle ADE is congruent to triangle CDB. This means that DE is congruent to DC implying D is the midpoint of CE.
