Hey there!
To start, first set up your expression like this:
(5x+17)-(3x-4)
You must set up your expression like this since in subtraction, order matters and the problem asks for the difference between the first plant and the second plant, respectively, meaning you must follow in this order.
Now, simplify:
(5x+17)-(3x-4)
(5x+17)+(-3x+4)
2x+21
Therefore, the difference the two companies would be 2x+21.
