Will mark three angles in a quadrilateral measure 31º, 83º, and 146º. what is the measure of the fourth angle? a. 82ºb. 97ºc. 100ºd. 112º

You'd need to know the degrees of a quadrilateral which is, 360 degrees.

I'm going to represent x as the degrees we need to find:

31+83+146+x=360
 
*add like terms*

260+x=360
x=100

The degrees of the angle is 100 degrees. Therefore, your answer is choice C.