We have

so this is indeed a difference of squares. Factorizing would give

making the answer D.
We can further factor the first term here and write

but that's clearly out of the scope of this question.
Firstly you have to reduce the 4 variables to a double system of equation with only 2 variables.
Let's say, first we have to eliminate Z:
Take 1st & 3rd equation & multiply each term of the 1st by (- 1). One done you add up the 1st & the 3rd & you will get:
5W - 4x + 2y = - 18
Follow the same methodology to find another equation without z. Once done you will have a system of 2 equation with 2 variable easy to solve,
At the end you will find:
w = -3
x = -2
y = -1
z = 3
Answer:
17 = x
Step-by-step explanation:
720 = 110 + 8x -1 + 5x + 36 + 116 + 7x + 19 + 6x - 2
720 = 278 + 26x
442 = 26x
17 = x