Question

look at this diagram:
if \\( \overleftrightarrow { c e } \\) and \\( \overleftrightarrow { f h } \\) are parallel lines and \\( m \angle e d g = 140 ^ { \circ } \\), what is \\( m \angle c d b \\)?

Explanation:

Step1: Use the property of supplementary angles

Since $\angle EDG$ and $\angle CDB$ are supplementary angles (they form a linear pair), the sum of their measures is $180^{\circ}$.
Let $m\angle CDB = x$. Then we have the equation $x + 140^{\circ}=180^{\circ}$.

Step2: Solve the equation for $x$

Subtract $140^{\circ}$ from both sides of the equation:
$x=180^{\circ}- 140^{\circ}$.

Answer:

$40$