Explain this and what method? Is it linear combos or some sort of GCF finding

Answer:
just subtracting the expression for revenue from the expression for cost
Step-by-step explanation:
2x^3 + 30x - 130
- 2x^3 - 3x - 520
(subtracting means adding the opposite)
2x^3 - 2x^3 = 0
30x - (-3x) = 33x
-130 - (-520) = 390