Answer:
1b
2b
3a
Step-by-step explanation:
 
        
             
        
        
        
The domain is all the numbers of which the inputs can be put. Here, we have a graph, which simplifies things. We just need to look at the x-values of the graph, or the horizontal line. The graph extends both negatively and positively. Thus since the graph extends both ways (right and left) forever, the answer would be D, or all real numbers.
        
             
        
        
        
Answer:
3(3a+15b)
Step-by-step explanation:
GCF: 3
Find all the prime factors between 3 and 15
3: 1,3 1*3
15: 1,3,5,15 (1*15 3*5)
3 is the GCF between the 2 numbers.
 
        
             
        
        
        
You are correct. The answer is choice C.
The other choices A, B, D have each side add up to 180 degrees either because the angles are a linear pair (adjacent and supplementary) or because the angles are same side interior angles. Same side interior angles are supplementary if a transversal line cuts through a pair of parallel lines as so happens in this diagram.