Answer:

Step-by-step explanation:
We know that for any two function f(x) and g(x) ,

Given functions :
and 
Then, 

At x= 6 , we get

The , The expression is equivalent to 
When we further simplify it , we get 
A) The result of adding the two equations is
.. (2.5y +3x) +(5x -2.5y) = (27) +(5)
.. 8x = 32 . . . . . . . . . . . . . . . . . . . . . . . your 2nd selection
b) The solution to the system is (4, 6), your 4th selection.
.. This is the only choice with x=4, the solution to part (a).
Christy will have to work 50 hours to pay off her debt.
500 divided by 10 = 50.
Hope this helped!