Profit is calculated by subtracting the total cost from the total revenue as expressed in the equation given above as,
P(x) = R(x) - C(x)
If we are to substitute the given expression for each of the terms, we have,
P(x) = x(S(x)) - C(x)
Substituting,
P(x) = x(30 - 0.01x) - (0.15x³ + 0.01x² + 2x + 120)
Simplifying,
P(x) = 30x - 0.01x² - 0.15x³ - 0.01x² - 2x - 120
Combining like terms,
P(x) = -0.15x³ - 0.02x² + 28x - 120
The answer to this item is the second among the choice, number 2.