C
By subtracting 18 to both sides you are separating the 3x because you are not ready to isolate the variable (x) in step 1
1.4 in thousands is 1.400

A parabola is open up if a > 0.
The vertex formula:

(h; k) - the coordinates of the vertex

Therefore h = -5 < 0
Answer: B. y = x² + 10x + 24.
Answer:

Explanation:
Combining the fractions, we have: