Question

∠acd and ∠dcb form a linear pair. if m∠dcb = 140°, then m∠acd = ?°

Explanation:

Step1: Recall linear - pair property

The sum of angles in a linear pair is 180°. So, $m\angle ACD + m\angle DCB=180^{\circ}$.

Step2: Solve for $m\angle ACD$

We know $m\angle DCB = 140^{\circ}$. Then $m\angle ACD=180^{\circ}-m\angle DCB$. Substitute $m\angle DCB = 140^{\circ}$ into the equation: $m\angle ACD = 180 - 140$.
$m\angle ACD=40^{\circ}$

Answer:

$40$