For question 10, find the measure of angle CED.

Solution:

In triangle CDE, the sum of angles is 180 degrees. We are given that angle DCE is 80 degrees.

The angle CEF is a straight angle, so it measures 180 degrees. Angle CED and angle DEF are supplementary angles.

We are given that angle DEF is 140 degrees.

Therefore, angle CED = 180 degrees - angle DEF = 180 degrees - 140 degrees = 40 degrees.

Now consider triangle CDE. The sum of angles in triangle CDE is 180 degrees:

Angle DCE + Angle CED + Angle CDE = 180 degrees

80 degrees + 40 degrees + Angle CDE = 180 degrees

120 degrees + Angle CDE = 180 degrees

Angle CDE = 180 degrees - 120 degrees = 60 degrees.

The question asks for the measure of angle CED.

Angle CED = 40 degrees.

Answer: 40 degrees