Answer:
Measure of angle x is 47°.
Explanation:
 We are given a triangle with measure of two angles given as 102° and 31°.
We have to find the value of third angle .
Angle sum property of a triangle states that the sum of angles of a triangle is always 180° 
Lets name the triangle first as ΔABC,
Applying angle sum property 
∠A + ∠B + ∠C = 180°
Substitute the values, we get,
x°+ 102° + 31° = 180°
x°+ 133° = 180°
x°= 180° - 133°
x° = 47° 
Thus, measure of angle x is 47°.