Answer:
E, F, B, and C
Step-by-step explanation:
Im just learning about these kind of things and this is a challenging question not going to lie.
I chose B because expanding and building more factories is apart of economics. You need more land to expand your business, but this will also affect the economy. 
C seems like a good answer also because writing about economic trends is an important thing in economics. This also helps others learn out the economy and what not to do and what to do to help make our environment a better place. 
I chose E because starting a business is apart of economics. A lot of business are apart of economic systems and help money come into our economy. 
F is a good answer for me because the U.S government has been apart of America's economic system for a long time just like they are involved with everything else. The government is a big help and a big part of our economy, especially for america. 
 
        
             
        
        
        
Answer: Both A, and C
Step-by-step explanation:
The answer to the first system of equations (2x+2y=16) would be 
x=3 and y=5 ( 3x-y=4 )
Which means we have to find out which of the other equations has an x value of 3, and a y value of 5.
If A is 2x+2y=16, then x=3 and y=5
            6x-2y=8
If B is x+y=16, then x=5 and y=11
          3x-y=4
If C is 2x+2y=16, then x=3 and y=5
            6x-2y=8
If D is 6x+6y=48 , then x=-2 and y=10
             6x+2y=8
Both A and C are equal to the first system of equations, which means they are both correct answers.
 
 
        
             
        
        
        
5 and above give it a shove, 4 and below let it go
So if the number in the tenths spot it 5 and above you round up, if it is 4 and below you take the whole number in the original number used and that is your answer. In this case the tenth spot is 5 so you round it to 90
        
                    
             
        
        
        
Its answer 3 because they are the only difference with two squared numbers