The answers with units

Suppose that for a company manufacturing calculators, the cost and revenue equations (in dollars) are given by C = 70,000 + 50x, R = 200x - 4,000 where the production output in one week is x calculators. If the production rate is increasing at a rate of 600 calculators per week when the production output is 4,000 calculators, find each of the following with correct units. (Note: Profit is revenue minus costs.) (a) The rate of change of the cost with respect to time is ---Select--- O . (b) The rate of change of the revenue with respect to time is ---Select--- (c) The rate of change of the profit with respect to time is ---Select