Answer:
9a+6b
Step-by-step explanation:
4a+7b+5a-b
First figure out the  a's 4a + 5a = 9a
Then do b's (Remember, if there is no number by the letter then it is 1) 
7b - 1b = 6b
So for this to be simplified the answer is 9a+6b
 
        
             
        
        
        
Y=mx+b
m=slope
the greater m is the steeper the graph
so the correct answer is B
        
             
        
        
        
Your domain is all positive numbers, and your range is all numbers. this is because no matter what you plug in for y, x will only ever get extremely close to 0, but never reach it or go below it, and if you put in large values of y x will get very big. 
 
        
        
        
The correct answer is 5.25