I need help in this question, please solve those two parts which are wrong

An industrial production process costs C(q) million dollars to produce 4 million units; these units then sell for R(q) million dollars. If C (2.1) = 5.3, R (2.1) = 6.9, MC (2.1) = 0.5, and MR(2.1) = 0.6, calculate the following. (a) The profit earned by producing 2.1 million units. The profit is 1.6 million dollars. (b) The approximate change in revenue if production increases from 2.1 to 2.14 million units. The change in revenue is about 124 thousand dollars. (c) The approximate change revenue if production decreases from 2.1 to 2.05 million units. The change in revenue is about thousand dollars. (d) The approximate change in profit in parts (b) and (c). The change in profit in part (b) is about 4 thousand dollars, and the change in profit in part (c) is about thousand dollars