How were these found? I am confused!!

The price-demand equation and the cost function for the production of table saws are given, respectively, by x = 5968 - 20p C(x) = 31x + 102133.8 where x is the number of saws that can be sold at a price of $p per saw and C(a ) is the total cost (in dollars) of producing a saws. A. Express the price, p, as a function of the demand, . x - 5968 P(= = -20 B. Find the revenue function, R(x). RT = x2- 5968x -0.05x2+ 298.4x -20 C. Find the profit function, P(x). P(x) = -0.05x + 267.4x + 102134 X -0.052 + 267.4x - 102133.8