The marginal revenue (in thousands of dollars) from the sale of x gadgets is given by the following function. The revenue from 130 gadgets is $56 376. 2 MR(x) = 4x (x + 30,000) (a) Find the revenue function. (b) What is the revenue from selling 250 gadgets? (c) How many gadgets must be sold for a revenue of at least 540 0007