Answer:
118°
Step-by-step explanation:
EDC is 31° and ECD has the same measure. (Triangle DEC is isosceles)
The total sum of angle EDC and ECD is 31 + 31 = 62°
The total sum of all the angle measures in a triangle is 180°, so just subtract 62 from 180 to get the measure of angle DEC.
180 - 62 = 118°
