Question

line ab is parallel to line de. determine each angle measure.

angle	measure (degrees)
$angle ecb$
$angle acb$

Explanation:

Step1: Use alternate - interior angles

Since $AB\parallel DE$, $\angle ACD$ and the angle adjacent to the $115^{\circ}$ angle at $A$ are alternate - interior angles. The angle adjacent to the $115^{\circ}$ angle at $A$ is $180 - 115=65^{\circ}$. So $\angle ACD = 65^{\circ}$.

Step2: Use vertical angles

$\angle ECB$ and the angle adjacent to the $115^{\circ}$ angle at $A$ are vertical angles. So $\angle ECB=65^{\circ}$.

Step3: Use the angle - sum property

$\angle ACB = 180-(65 + 35)=80^{\circ}$

Answer:

Angle	Measure (degrees)
$\angle ECB$	$65$
$\angle ACB$	$80$