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.
The slope is 3/1
hope this helps
Answer:
18
Step-by-step explanation:
Juan’s lunch would have costed less if he paid separately. his lunch is 5.25
the bill 37.20
37.20 / 5
$7.44 each kid
7.44 - 5.25 = 2.19
$2.19 less if he paid separately