Answer:
Part A: D. 

Part B: Smaller angle 
 , larger angle
, larger angle 
 
 
Step-by-step explanation:
The term supplementary is used when the sum of two angles add to 
 .
.
Part A:
From the information given that the "angles are supplementary" and the "measure of one angle is 3 times the measure of the other", the equation to find for x can be written as:

Part B:
To find the measure of each angle, we can first find the measure of the smaller angle 
 :
:



 The smaller angle is
 The smaller angle is 

Since the measure of the larger angle is 
 times the measure of the smaller angle:
 times the measure of the smaller angle:
Larger angle 



 The measure of the larger angle is
 The measure of the larger angle is 

Hope this helps :)