Consider the difference between the angles the two rays points to on the protractor.
Correct angle: 25^(∘) Explanation: See solution.
Practice makes perfect
Let's start by marking ∠ DOE on the protractor. This is the angle that's in between the rays that starts at O and passes through the points D and E.
Using the inside measurements on the protractor, the ray through D points to 65^(∘) and the ray through E points to 40^(∘). The measure of ∠ DOE is going to be the difference between these angles
65^(∘)-40^(∘)=25^(∘).
The error made was to only consider the angle that the ray through D points to, and not the difference between the angle that D and E measures.
