Final answer:
Upon equating the revenue function to the cost function and solving for x, it is found that revenue equals cost at the production level of x = 350 units, which is not one of the provided options.
Step-by-step explanation:
To find at what production level revenue at least equals cost, we set the revenue equation equal to the cost equation and solve for x. The revenue equation is R = 45x, and the cost equation is C = 30x + 5250.
Equating the two gives us 45x = 30x + 5250.
Simplifying this equation we get 15x = 5250, thus x = 350.
Therefore, the production level at which revenue at least equals cost is x = 350, which is not one of the provided options (A, B, C, D).
It suggests there might be a mistake in the question or the options provided.